Add the cake mix, vegetable oil, and eggs to a large bowl or stand mixer fitted with a paddle attachment and beat until combined.
Divide the dough into the number of different colors you want, in this recipe, we did 5.
Mix each portion of dough with the desired color. Using a single hand mixer beater will give you the most even color and easiest mixing method.
Chill the dough for 45 minutes.
Preheat the oven to 350 degrees F and line a baking sheet with parchment paper.
Use two teaspoons to portion out the dough into dollops, using the spoons to work the dough back and forth between them until the dough drops onto the parchment since it will be very sticky. Drop one dollop of each color dough per cookie.
Use a medium cookie scoop to scoop the dollops together then gently roll into balls, you want to avoid getting food coloring all over your hands. Then roll the balls in the sugar to coat. Place the balls of dough on the prepared baking sheet at least 2 inches apart.
Bake for 8 to 9 minutes. Do not over bake these cookies, they will look puffy and slightly underdone, but they will finish cooking on the baking sheet after coming out of the oven.
Let the cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.
Keep the cookies stored in an airtight container at room temperature for up to a week.