Cook the pasta: Cook the pasta according to the package instructions until al dente. Drain and set aside.
Prepare the deviled egg mixture: In a medium bowl, whisk together the mayonnaise, Dijon mustard (if using), salt, and pepper.
Add the chopped herbs: Stir in the chopped fresh dill, chives, and parsley.
Add the diced eggs: Stir in the diced hard-boiled eggs.
Add the diced vegetables: Stir in the diced red bell pepper and cucumber.
Combine the pasta and deviled egg mixture: In a large bowl, combine the cooked pasta, deviled egg mixture, and chopped herbs.
Toss to combine: Toss the pasta salad to combine all the ingredients.
Chill the salad: Chill the salad in the refrigerator for at least 30 minutes to allow the flavors to meld.
Serve: Serve the Deviled Egg Pasta Salad chilled, garnished with additional chopped fresh herbs if desired.