CUT each cake layer horizontally in half.
POUR milk into large bowl. Add dry pudding mixes. Beat with wire whisk 2 minutes or until well blended. (Mixture will be thick.) Stir in 1 cup of the coconut.
PLACE 1 of the bottom cake layers on serving plate; cover with 1/3 of the pudding mixture. Repeat cake and pudding layers 2 times; top with remaining cake layer. Stir remaining coconut into whipped topping; spread over top of cake. Refrigerate at least 1 hour or until ready to serve. Store leftover cake in refrigerator.