diff --git a/wp/lib/bap_wp/src/constraint.ml b/wp/lib/bap_wp/src/constraint.ml
index 34b7ff1a..cc4f9c16 100644
--- a/wp/lib/bap_wp/src/constraint.ml
+++ b/wp/lib/bap_wp/src/constraint.ml
@@ -19,7 +19,6 @@ module Bool = Z3.Boolean
 module BV = Z3.BitVector
 module Model = Z3.Model
 module Solver = Z3.Solver
-
 type z3_expr = Expr.expr
 
 type path = bool Jmp.Map.t
@@ -47,9 +46,17 @@ let get_model_exn (solver : Solver.solver) : Model.model =
     ~message:(Format.sprintf "Unable to get the model from the Z3 solver : %s"
                 (Solver.to_string solver))
 
-let goal_to_string (g : goal) : string =
-  Format.sprintf "%s: %s%!" g.goal_name (Expr.to_string (Expr.simplify g.goal_val None))
-
+let goal_to_string ?colorful:(colorful = false) (g : goal) : string =
+  let rm_backslash = String.substr_replace_all ~pattern:"\\" ~with_:"" in 
+  let lhs = g.goal_name |> rm_backslash in 
+  let rhs = (Expr.to_string (Expr.simplify g.goal_val None)) |> rm_backslash in
+  if colorful then
+    (* lhs is blue, rhs is cyan *)
+    Format.sprintf "%s%s%s: %s%s%s%!"
+      ("\x1b[1;34m") lhs ("\x1b[0m") ("\x1b[1;36m") rhs ("\x1b[0m")
+  else Format.sprintf "%s: %s" lhs rhs
+
+  
 let expr_to_hex (exp : z3_expr) : string =
   let decimal = BV.numeral_to_string exp in
   let size = exp |> Expr.get_sort |> BV.get_size in
@@ -183,25 +190,105 @@ type t =
   | Clause of t list * t list
   | Subst of t * z3_expr list * z3_expr list
 
-let rec pp_constr (ch : Format.formatter) (constr : t) : unit =
-  match constr with
-  | Goal g -> Format.fprintf ch "%s" (goal_to_string g)
-  | ITE (tid, e, c1, c2) ->
-    Format.fprintf ch "ITE(%s, %s, %a, %a)"
-      (tid |> Term.tid |> Tid.to_string) (Expr.to_string e) pp_constr c1 pp_constr c2
-  | Clause (hyps, concs) ->
-    Format.fprintf ch "(";
-    (List.iter hyps ~f:(fun h -> Format.fprintf ch "%a" pp_constr h));
-    Format.fprintf ch ") => (";
-    (List.iter concs ~f:(fun c -> Format.fprintf ch "%a" pp_constr c));
-    Format.fprintf ch ")"
+(* preen_expr expr will improve the readability
+   of expr by getting rid of white space 
+   and simplifying the expression. *)
+let preen_expr (expr : Expr.expr) : string =
+  Expr.simplify expr None
+  |> Expr.to_string
+  |> String.substr_replace_all ~pattern:"  " ~with_:""
+
+(* delete_empty_constr_hyps const will remove 
+   some empty lists in Clause constructs. For example
+   Clause([],Clause[Clause([],[x]),y]) becomes 
+   Clause([],Clause[x,y]). *)
+let rec del_empty_constr_hyps (const : t) : t =
+  match const with
+  | Clause(hyps,concs) ->
+    let fold_list c_list =
+      List.fold_right c_list ~init:[]
+        ~f:(fun x y ->
+          match x with
+          | Clause([],xs) ->
+             List.append (List.map xs ~f:del_empty_constr_hyps) y
+          | _ -> (del_empty_constr_hyps x) :: y) in
+    Clause(fold_list hyps, fold_list concs)
+  | Goal g -> Goal g
+  | ITE (ite, e, c1, c2) ->
+     let new_c1 = del_empty_constr_hyps c1 in
+     let new_c2 = del_empty_constr_hyps c2 in
+     ITE (ite, e, new_c1, new_c2)
   | Subst (c, olds, news) ->
-    Format.fprintf ch "Substitute: %s to %s in %a"
-      (List.to_string ~f:Expr.to_string olds) (List.to_string ~f:Expr.to_string news)
-      pp_constr c
-
-let to_string (constr : t) : string =
-  Format.asprintf "%a" pp_constr constr
+     let new_c = del_empty_constr_hyps c in
+     Subst (new_c, olds, news)
+
+(* to_color colorful ch c str ins will print str with insert
+   ins and formatter ch. If colorful is true, then this will 
+   print in the color c. *)
+let to_color (colorful : bool) (ch : Format.formatter) (c : int)
+      (str : ('a -> 'b, Format.formatter, unit) Stdlib.format)
+      (ins : string) : unit =
+    if colorful then Format.fprintf ch "\x1b[1;%dm" c;
+    Format.fprintf ch str ins;
+    if colorful then Format.fprintf ch "\x1b[0m"
+
+(* print_expr_list expr_list ch converts expr_list into a list of 
+   strings of expressions and then prints each one on a new line 
+   using the formatter ch *)
+let print_expr_list (expr_list : Expr.expr list)
+      (ch : Format.formatter) : unit =
+  let expr_string_list : string list =
+    List.map expr_list ~f:(fun e -> preen_expr e |> String.split_lines)
+    |> List.join in
+  let rec print_exprs ch exprs =
+    match exprs with
+    | [] -> ();
+    | [e] -> Format.fprintf ch "%s" e
+    | e :: es -> Format.fprintf ch "%s@;" e ; print_exprs ch es in 
+  Format.fprintf ch "@[<v 2>%a@]" print_exprs expr_string_list
+
+let pp ?colorful:(colorful = false) (_ : unit)
+      (fmt : Format.formatter) (t : t) : unit =
+  let rec rec_pp ch constr =
+    let to_color = to_color colorful ch in
+    match constr with
+    | Goal g ->
+       Format.fprintf ch "%s@;" (goal_to_string ~colorful g)
+    | ITE (tid, e, c1, c2) ->
+       let color = 35 in (* magenta *)
+       to_color color "%s: (if " (tid |> Term.tid |> Tid.to_string);
+       Format.fprintf ch "%s" (preen_expr e);
+       to_color color " then%s" "";
+       Format.fprintf ch "@[@;%a@]" rec_pp c1;
+       to_color color " else%s" "";
+       Format.fprintf ch "@;%a" rec_pp c2;
+       to_color color ")%s" "";
+    | Clause (hyps, concs) ->
+       (if not (List.is_empty hyps) then 
+         let print_hyps =
+           List.iter hyps
+             ~f:(fun h -> Format.fprintf ch "%a" rec_pp h) in
+         print_hyps; 
+         let color = 33 in (* yellow *)
+         to_color color " => %s" "") ;
+       (List.iter concs ~f:(fun c -> Format.fprintf ch "%a" rec_pp c));
+    | Subst (c, olds, news) ->
+       let color = 32 in (* green *)
+       to_color color "(let %s" "";
+       Format.fprintf ch "%s" (List.to_string ~f:(preen_expr) olds);
+       to_color color " = %s" "";
+       print_expr_list news ch;
+       to_color color " in%s" "";
+       Format.fprintf ch "@;%a" rec_pp c;
+       to_color color ")%s" "";
+  in
+  rec_pp fmt (del_empty_constr_hyps t)
+  
+let to_string ?(colorful=false) (constr : t) : string =
+  let pp_constr = pp ~colorful:colorful () in 
+  Format.asprintf "%a" pp_constr constr 
+  |> String.substr_replace_all ~pattern:"\"" ~with_:""
+  |> Scanf.unescaped 
 
 let mk_constr (g : goal) : t =
   Goal g
diff --git a/wp/lib/bap_wp/src/constraint.mli b/wp/lib/bap_wp/src/constraint.mli
index 660343b9..ce2aa39a 100644
--- a/wp/lib/bap_wp/src/constraint.mli
+++ b/wp/lib/bap_wp/src/constraint.mli
@@ -57,7 +57,7 @@ type refuted_goal
 val mk_goal : string -> z3_expr -> goal
 
 (** Creates a string representation of a goal. *)
-val goal_to_string : goal -> string
+val goal_to_string : ?colorful:bool -> goal -> string
 
 (** Creates a string representation of a Z3 numeral as a hexadecimal in BAP notation. *)
 val expr_to_hex : z3_expr -> string
@@ -87,10 +87,10 @@ val get_goal_name : goal -> string
 val get_goal_val : goal -> z3_expr
 
 (** Creates a string representation of a constraint. *)
-val to_string : t -> string
+val to_string : ?colorful:(bool) -> t -> string
 
 (** Pretty prints a constraint. *)
-val pp_constr : Format.formatter -> t -> unit
+val pp : ?colorful:bool -> unit -> Format.formatter -> t -> unit
 
 (** Creates a constraint made of a single goal. *)
 val mk_constr : goal -> t
diff --git a/wp/lib/bap_wp/src/precondition.ml b/wp/lib/bap_wp/src/precondition.ml
index 575b4241..b7097b11 100644
--- a/wp/lib/bap_wp/src/precondition.ml
+++ b/wp/lib/bap_wp/src/precondition.ml
@@ -1317,7 +1317,8 @@ let check ?(refute = true) ?(print_constr = []) ?(debug = false) ?ext_solver
   Format.fprintf fmt "Evaluating precondition.\n%!";
 
   if (List.mem print_constr "precond-internal" ~equal:(String.equal)) then (
-    Printf.printf "Internal : %s \n %!" (Constr.to_string pre) ) ;
+    let colorful = List.mem print_constr "colorful" ~equal:String.equal in  
+    Printf.printf "Internal : %s \n %!" (Constr.to_string ~colorful:colorful pre) ) ;
   let pre' = Constr.eval ~debug:debug pre ctx in
   Format.fprintf fmt "Checking precondition with Z3.\n%!";
   let is_correct =
diff --git a/wp/lib/bap_wp/tests/performance/test_precondition.ml b/wp/lib/bap_wp/tests/performance/test_precondition.ml
index a1211a60..cf13132a 100644
--- a/wp/lib/bap_wp/tests/performance/test_precondition.ml
+++ b/wp/lib/bap_wp/tests/performance/test_precondition.ml
@@ -62,7 +62,7 @@ let time_z3_result (test_ctx : test_ctxt) (z3_ctx : Z3.context) (body : Sub.t)
     ~printer:Solver.string_of_status
     ~pp_diff:(fun ff (exp, real) ->
         Format.fprintf ff "\n\nPost:\n%a\n\nAnalyzing:\n%sPre:\n%a\n\n%!"
-          Constr.pp_constr post (Sub.to_string body) Constr.pp_constr pre;
+          (Constr.pp ()) post (Sub.to_string body) (Constr.pp ()) pre;
         print_z3_model ff solver exp real)
     expected result;
   let time = end_time -. start_time in
diff --git a/wp/lib/bap_wp/tests/unit/test_compare.ml b/wp/lib/bap_wp/tests/unit/test_compare.ml
index 8684ff00..2d25a5b7 100644
--- a/wp/lib/bap_wp/tests/unit/test_compare.ml
+++ b/wp/lib/bap_wp/tests/unit/test_compare.ml
@@ -37,7 +37,7 @@ let assert_z3_compare (test_ctx : test_ctxt) (body1 : string) (body2 : string)
     ~printer:Z3.Solver.string_of_status
     ~pp_diff:(fun ff (exp, real) ->
         Format.fprintf ff "\n\nComparing:\n%s\nand\n\n%s\nCompare_prop:\n%a\n\n%!"
-          body1 body2 Constr.pp_constr pre;
+          body1 body2 (Constr.pp ()) pre;
         print_z3_model solver exp real pre ~orig:env1 ~modif:env2)
     expected result
 
diff --git a/wp/lib/bap_wp/tests/unit/test_precondition.ml b/wp/lib/bap_wp/tests/unit/test_precondition.ml
index 80b9185e..221cd366 100644
--- a/wp/lib/bap_wp/tests/unit/test_precondition.ml
+++ b/wp/lib/bap_wp/tests/unit/test_precondition.ml
@@ -37,7 +37,7 @@ let assert_z3_result (test_ctx : test_ctxt) (env : Env.t) (body : string)
     ~printer:Z3.Solver.string_of_status
     ~pp_diff:(fun ff (exp, real) ->
         Format.fprintf ff "\n\nPost:\n%a\n\nAnalyzing:\n%sPre:\n%a\n\n%!"
-          Constr.pp_constr post body Constr.pp_constr pre;
+          (Constr.pp ()) post body (Constr.pp ()) pre;
         print_z3_model solver exp real pre ~orig:env ~modif:env)
     expected result
 
diff --git a/wp/plugin/lib/wp_parameters.ml b/wp/plugin/lib/wp_parameters.ml
index 491110c7..2fda8f2d 100644
--- a/wp/plugin/lib/wp_parameters.ml
+++ b/wp/plugin/lib/wp_parameters.ml
@@ -92,7 +92,8 @@ let validate_show (show : string list) : (unit, error) result =
     "refuted-goals";
     "paths";
     "precond-internal";
-    "precond-smtlib"
+    "precond-smtlib";
+    "colorful"
   ] in
   match find_unsupported_option show supported with
   | Some s ->
diff --git a/wp/plugin/wp.ml b/wp/plugin/wp.ml
index 448f218e..c88f5566 100644
--- a/wp/plugin/wp.ml
+++ b/wp/plugin/wp.ml
@@ -185,8 +185,13 @@ let show = Cmd.parameter Typ.(list string) "show"
            format.
 
            `precond-internal': The precondition printed out in WP's internal
-           format for the `Constr.t' type.|}
+           format for the `Constr.t' type.
 
+           `colorful': precond-internal can have color to highlight key words,
+           making the output easier to read. Warning: Coloring will change
+           the syntax, so don't use this flag if you wish to pass the printed
+           output as an input elsewhere.|}
+         
 let stack_base = Cmd.parameter Typ.(some int) "stack-base"
     ~doc:{|Sets the location of the stack frame for the function under
            analysis. By default, WP assumes the stack frame for the current
diff --git a/wp/resources/sample_binaries/nested_function_calls/run_wp_inline_all.sh b/wp/resources/sample_binaries/nested_function_calls/run_wp_inline_all.sh
index 2cb66963..7f65003a 100755
--- a/wp/resources/sample_binaries/nested_function_calls/run_wp_inline_all.sh
+++ b/wp/resources/sample_binaries/nested_function_calls/run_wp_inline_all.sh
@@ -8,6 +8,7 @@
 run () {
   bap wp \
     --func=main \
+    --show=precond-internal \
     --inline=.* \
     --trip-asserts \
     -- ./bin/main