Show your Colors with this Rainbow roll! All you need is one box of white Cake Mix, food colorings of your choice, icing and sprinkles. Separate the cake mix into one bowl for each color and mix. Then pour the colored batter into a zip lock baggie and trim the very edge off. Then grab a color and start a line from one corner to the other to us as your baseline. Then alternate colors on each side of the baseline until the pan if full. Tap the pan on the counter a few times to get out any air bubbles that may be between each color. Bake at 275 for 10 minutes or until done in the center. Let cool completely and layer with icing and sprinkles. Roll up and slice!