If you want to decorate the cakes in the three colors you will with need to make your swirls very small or make another half batch of frosting.
Reserve 2/3 cup of white frosting
Divide the remaining frosting in half and tint one orange and one yellow
Place the three frostings in piping bags with a #1m Wilton tip
On the cupcake pipe the yellow, then orange and white on top , getting smaller as you go up like a candy corn
Top with a candy corn and sprinkles