Preheat oven to 325°. Line 12 muffin cups with paper liners. Prepare cake mix according to package directions.

Divide batter into six separate bowls, tinting each with food coloring to make purple, blue, green, yellow, orange and red batter. Fill prepared cups two-thirds full, alternating tablespoonfuls of colored batter.

Bake 18-22 minutes or until a toothpick inserted in center comes out clean. Cool in pans 10 minutes before removing to wire racks to cool completely.

In a bowl, beat cream until it begins to thicken. Add confectioners' sugar and vanilla; beat until soft peaks form. If desired, using a new small paintbrush, paint five stripes with food coloring inside a pastry bag fitted with a round tip. Fill bag with whipped cream. Pipe over cupcakes.