In a medium mixing bowl or stand mixer, prepare white cake mix according to package directions.
Separate mixture evenly into two bowls.
Add a bit of purple food coloring to one bowl until you get the color you would like. Repeat with the pink coloring.
Mix coloring thoroughly until well blended and smooth
Spray 9x13 baking dish. Spoon your colored cake mix in random “plops” into the pan.
Using wooden toothpick or skewer, make swirl patterns into the mixture. Do not be tempted to "overswirl" or your cake won't show its pattern well.
Bake according to package directions and allow to cool completely.
Poke holes into the cooled cake with the round end of a wooden spoon.
Prepare both boxes of pudding according to package directions. Pour the pudding over the cake. It will fill the holes you poked and form a thin layer on top of the cake.
Add candy melts to two separate bowls. Add 1 tablespoon of vegetable oil or heavy whipping cream to each bowl. Melt in 30 second intervals in microwave until completely melted and mix until smooth. Drizzle the melted candy over the top of the cake in whatever pattern you like. Let cool.
Evenly spread the whipped topping to the top of the cake
If desired, sprinkle the colored sugar or sprinkles over the top of the cake.
Refrigerate until set, about 60 minutes.