Preheat oven to 350 degrees F (175 degrees C).

Stir cake mix, water, eggs, and vegetable oil together in a bowl until moistened; beat the batter with an electric mixer set on medium speed for 2 minutes.

Divide cake batter into 4 equal portions in separate bowls. Tint each bowl a different color, stirring in red, green, yellow, and blue food coloring to reach desired shade.

Set ice cream cones upright in 24 muffin cups.

Spoon about 1 1/2 tablespoons of each colored batter into cones, leaving about 1 inch of room from the top.

Carefully transfer cones to the preheated oven and bake until a toothpick inserted into the middle of a filled cone comes out clean, 20 to 25 minutes.

Cool cupcakes thoroughly before decorating, about 1 hour.