PREPARE cake batter and bake as directed on package for 13x9-inch pan, lining pan with foil sprayed with cooking spray before adding batter. Cool cake in pan 15 min.; invert onto wire rack. Cool completely. Place on platter.
TINT 2 cups COOL WHIP with food coloring; spread onto top and sides of cake. Spoon remaining COOL WHIP into resealable bag. Cut off small piece from 1 bottom corner of bag; use to outline football field on top of cake. Add yard lines with remaining white COOL WHIP.
ADD bear-shaped graham snacks for the football players and OREO Cookie for the football. Thread marshmallows onto toothpicks; use to make goal posts as shown in photo. Add to top of cake. Keep refrigerated. Remove and discard toothpicks before serving.