Preheat the oven to 350 degrees Fahrenheit and spray a 9X5 loaf pan with a non-stick cooking spray.
In a large mixing bowl, whisk together the flour, baking soda and salt.
In a separate bowl, beat together the butter and sugar with a hand held mixer or stand up mixer.
Mix in the eggs (one at a time) until combined. Then mix in the mashed bananas.
Gradually add in the flour mixture until just combined. Be careful not to over mix.
Divide the batter evenly into 4 small bowls. Use the food coloring to dye each bowl a different color. 1 pink, 1 purple, 1 green and 1 blue. Add the food coloring until each one is a vibrant color.
Scoop a few dollops of each of the different batters into the loaf pan. Then sprinkle some sprinkles on top. Continue this process until all of the batters are used.
Bake for 50-65 minutes until a toothpick inserted into the center of the bread comes out clean.
Cool the bread in the bread pan for 10-15 minutes and then move to a wire rack to cool completely.
For the icing, whisk together the powdered sugar and milk. Pour this mixture over the cooled bread and top with Rainbow sprinkles.
Let sit until the icing cools and then the bread is ready to slice, serve and enjoy!