Make the cake according to the package instructions. Pour the batter into whatever
size cake pan(s) that you want. Scatter drops of different food colors over the
top of the batter. Use a butter knife to cut through the batter using a swirling
motion. This will blend in and mix up the colors.
Bake the cake and cool.
Frost with white frosting. Scatter dots of food coloring over the frosting. Then
use a wooden pick and swirl the colors into the frosting.