Preheat oven to 350°F. In a large bowl, beat eggs for 5 minutes, and add in the sour cream, cake mix, oil, and water. Mix until consistent, and there are no lumps.

Take six bowls, and pour the batter in each of the bowls. Place red, orange, yellow, green, blue, purple food colorings into each of the bowls. 

Pour each of the colored batters into pastry bags, and pipe a thin layer of batter into each of your baking sheets. Bake in the oven for 10-15 minutes.

Dust two kitchen towels with powdered sugar. Remove the cakes from the oven, and quickly flip them onto each of the towels. Immediately roll up the cakes, making sure to peel away the tin foil/parchment paper. Let the cakes sit for 30 minutes.

While they are cooling, in a small bowl, mix together cool whip and whipped frosting. Add sprinkles of your choice.

Unroll the cakes, and spread half of the frosting onto each of the cakes and roll the cakes into logs. Enjoy!