Yield: 18 Servings (3 points per serving for blue, green and purple)
In a medium bowl whisk together the cake mix and Diet 7 Up until smooth.
Spray a 9 x 13 baking pan with non-stick cooking spray then add the batter. Cook cake according to the directions on the box.
When the cake comes out of the oven let it cool for 15 minutes. While the cake is cooling boil 1 cup of water. Add the boiling water to the Jell O. Stir until completely dissolved (3 minutes). Then add 1 cup of cold water and stir.
Poke holes into the top of the cake using a fork. Pour the Jell O evenly over the cake.
Refrigerate for 3 hours.
Spread Cool Whip across the top then serve.