In large bowl, beat cake mix, water, oil and eggs with electric mixer on medium speed 2 minutes, scraping bowl occasionally. In small bowl, pour 1 ¼ cups of the batter; stir in 2 tablespoons cocoa until blended. In another small bowl, pour 1 ¼ cups of the batter; stir in 2 tablespoons strawberry jam and ¼ teaspoon food color until blended. Pour remaining cake batter in bottom of pan. Drop tablespoons of each colored batter in random pattern over top; pull table knife through batter to make swirls.