Prepare cake according to the package directions and bake in 9 x 13 x 2 inch baking pan. Cool 20 minutes and remove from an onto large platter or jelly roll pan. With toothpick make holes in cake at 1 inch intervals. Heat evaporated milk, sugar and flavoring and pour over cake. Cover with plastic wrap and place in refrigerator overnight so that cake will completely absorb sugar-milk mixture. The next day spread whipped topping over top and sides of cake. Sprinkle on coconut. Refrigerate until ready to serve. May be served as is or topped with fresh strawberries or peaches.