Divide the cream cheese into 5 separate small bowls. To make blue cream cheese, add spirulina to one bowl and stir gently. Add matcha tea to the second bowl to make green. Add turmeric powder to the third bowl to make yellow. Add red cabbage juice and baking soda to the fourth bowl to make purple. Add beet juice to the last bowl to make pink.
Spread the different colors on the toast to create a rainbow effect, and decorate as desired.