Begin by bringing a large pot of salted water to a rolling boil. Add elbow macaroni and cook for 8 to 10 minutes, or until al dente. Once cooked, drain and rinse under cold water.

In a medium mixing bowl, combine mayonnaise and Dijon mustard. Add salt and pepper to taste, then whisk until smooth and creamy.

Transfer cooled macaroni to the bowl with the dressing. Fold the pasta into the creamy mixture, then add bell peppers, celery, cherry tomatoes, red onion, and sweet pickle relish. Stir to combine.

Cover the bowl with plastic wrap and place it in the refrigerator for at least 1 hour to let the flavors meld.