Heat oven to 350°F. Generously spray 12-cup fluted tube cake pan with baking spray with flour.
In large bowl, beat cake mix, water, oil and whole eggs with electric mixer on medium speed 2 minutes, scraping bowl occasionally. In small bowl, place 1 cup of the batter; stir in 1 teaspoon of the red food color until blended. In another small bowl, place 1 cup of the batter; stir in 1 teaspoon of the blue food color until blended.
Pour red cake batter into bottom of pan. Carefully pour remaining white batter over red batter in pan. Carefully pour blue batter over white batter. (Blue batter does not need to cover white batter completely; it looks better if it just forms a ring in the center of the white batter.)
Bake 40 to 45 minutes or until toothpick inserted in center comes out clean. Remove cake from oven. Let stand 10 minutes, remove from pan to cooling rack. Cool completely, about 1 hour.
Place cake on cooling rack over waxed paper or cooking parchment paper. In small microwavable bowl, place 1/4 cup of the frosting. Microwave uncovered on High 10 to 15 seconds or until thin enough to drizzle over cake. With spoon, drizzle warmed frosting back and forth over cake in striping pattern. Divide remaining frosting between 2 small microwavable bowls. To 1 bowl, stir in 1/4 teaspoon red food color until well blended. Microwave uncovered on High 5 to 10 seconds or until thin enough to drizzle. Drizzle over cake. Repeat with remaining bowl of frosting and 1/4 teaspoon blue food color. Sprinkle candy sprinkles on top. Let stand about 30 minutes or until frosting is set. Store loosely covered at room temperature.