Preheat oven to 325°F (160°C).

Line 12 muffin cups with paper liners.

Prepare white cake mix according to package directions.

Divide batter into six separate bowls.

Tint each bowl with food coloring to make purple, blue, green, yellow, orange, and red batter.

Fill prepared muffin cups two-thirds full, alternating tablespoonfuls of colored batter.

Bake for 18-22 minutes, or until a toothpick inserted in the center comes out clean.

Cool in pans for 10 minutes before removing to wire racks to cool completely.

In a bowl, beat heavy whipping cream until it begins to thicken.

Add confectioners' sugar and vanilla extract.

Beat until soft peaks form.

If desired, use a new small paintbrush to paint five stripes with food coloring inside a pastry bag fitted with a round tip.

Fill the bag with whipped cream.

Pipe the whipped cream over the cooled cupcakes.