Preheat oven to 350°. Prepare and bake cake mix according to package directions, using a 13x9-in. baking pan., Meanwhile, in a small bowl, mix cream of coconut and milk. Remove cake from oven; place on a wire rack. Using a wooden skewer, pierce top of cake to within 1 inch of edge; twist skewer gently to make slightly larger holes. Spoon milk mixture evenly over cake, being careful to fill each hole. Cool completely., Spread whipped topping over cake; sprinkle with coconut. Refrigerate until serving.