Follow directions on cake mix box for making cake. Bake the cake according to package instructions in a 13x9 pan. Then allow to cool.
Poke holes in the top of the cake with the handle of a wooden spoon or wide straw.
In one bowl add the blue gelatin and in another bowl add the red gelatin. Pour one cup of boiling water into each bowl and stir until dissolved. Then spoon half of each color gelatin over the cake (reserve the other half), making sure to spoon into the holes. The best way to do this is a row of blue, then a row of red and alternate so you get a colorful mix of red and blue in the cake.
Next, in two separate bowls, mix together 8 ounces cream cheese, ¼ cup powdered sugar and the remaining gelatin. Red in one bowl and blue in the other. To adjust the color, feel free to add red or blue food coloring to reach the shade you desire. Gel food coloring work best.
Spread the red cream cheese mixture over the cake then spread a layer of the blue cream cheese mixture.
Top with whipped topping and red, white and blue sprinkles.
Chill for 4 hours before serving.