Line 24 muffin cups with paper cupcake liners in school colors.
Place white cake mix into a large mixing bowl and beat in water, eggs, and vegetable oil with an electric mixer on low speed just until moistened. Turn mixer speed to medium and beat for 2 minutes.
Pour batter into prepared muffin cups, filling them about 2/3 full.
Bake cupcakes in the preheated oven until a toothpick inserted into the center of a cupcake comes out clean, 18 to 22 minutes.
Cool cupcakes thoroughly. Place cupcakes on a platter with the bottom sides facing up.
To decorate the cupcakes, break graham crackers in half to make 24 2 1/2-inch squares. Place a dab of frosting centered on bottom of each cupcake and stick a square to the frosting to form mortarboard part of a graduation cap.
Place the opened container of frosting into a microwave oven and heat until the frosting is warmed, soft, and workable, about 10 seconds. Frosting should be smooth but not runny. Color the frosting to your desired shade with food coloring.
Frost the top and sides of the graham cracker squares.
Unwrap lemon candies and place 2 candies onto a piece of waxed paper. Microwave the candies until warm and soft, 5 seconds or as needed.
Roll out the candies on waxed paper to make thin squares of candy. Using a sharp knife or small scissors, cut small tassel shapes from each square. When the tassels are made, set them aside and microwave 2 more candies; repeat steps until you have made 24 small candy tassels.
Place a tassel in the center of each graham cracker square. The tassel should hang slightly over the edge of the square.
Dip marked side of a candy-coated chocolate piece into frosting and place the piece onto the center of the graham cracker square, frosted side up, to cover the end of the candy tassel string.
Refrigerate decorated cupcakes to set the frosting. Store covered.