In trifle bowl or 3-quart glass bowl, layer one-third of the cake cubes and sour cream mixture. Top with half of the sweet potato mixture and 1 tablespoon coconut. Repeat layers once. Top with remaining cake cubes, sour cream mixture, coconut and the pecans. Repeat layers once. Sprinkle with remaining 1 tablespoon coconut and the pecans. Cover; refrigerate at least 1 hour.