Preheat oven to 350°F (175°C). Grease and line three 8-inch round cake pans with parchment paper.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
In a large bowl, cream together butter and sugar until light and fluffy (2–3 minutes).
Beat in eggs one at a time, then add vanilla.
Add dry ingredients in three parts, alternating with buttermilk, beginning and ending with the dry ingredients. Mix until just combined.
Divide batter evenly into three bowls:
Leave one plain (white layer).
Tint one orange.
Tint one yellow.
Pour each batter into its own prepared pan and smooth the tops.
Bake for 20–24 minutes, or until a toothpick inserted in the center comes out clean.
Let cakes cool in the pans for 10 minutes, then turn out onto wire racks to cool completely.