Preheat oven to 350 degrees.
Spray 9x13-inch baking pan with cooking spray.
In a mixing bowl; combine mochiko with sugar and baking powder.
Stir in water, coconut milk and vanilla extract.
Stirring to combine well.
Divide mixture equally into 3 portions, using stainless steel bowls for 2 portions.
Into stainless steel bowls; add 6 drops green coloring into 2nd bowl and 6 drops and red food coloring into 3rd bowl.
Layer 1st colored mixture.
Cover with foil; bake 15 minutes.
Remove foil; top with white mixture.
Cover and return to oven 20 minutes.
Remove foil and top with final colored mixture.
Cover and return to oven to bake additional 30 minutes.