Preheat oven to 350 degrees F. Coat a Bundt pan with cooking spray. Add sprinkles to prepared batter. Stir quickly then pour into Bundt pan and bake according to package directions. Allow to cool slightly then remove to a wire rack. Allow to cool completely.
Cut cake into three equal pieces. In a medium bowl,combine frosting and food color. Mix well. Place cake pieces flat-side down on a serving plate. Connect cut edges with colored frosting to form an "S" shape. Frost the cake. Then,if desired,give it a textured look by dragging the back of a spoon back and forth over the top of the cake,making ridges.
Press the Snowball onto one end of the cake to form a head. Stick one purple gumdrop on the end of each pretzel stick and stick them into the top of the head as antennae. Secure the yellow gumdrop eyes to the head with toothpicks. Slice the red gumdrop in half horizontally then in half vertically.
Secure one piece of the red gumdrop with a toothpick to form the mouth (eat or discard the remaining red gumdrop pieces). Press large ends of candy corn into frosting just behind the head to form the ruff around the head. Place peanuts in clusters of three along both sides of caterpillar cake to form feet. Crush some chocolate graham crackers and spread them on the platter around the cake to make it look like your "caterpillar" is crawling in soil!