What color of light has the most energy?

Violet.
Violet waves have the most of the visible spectrum.
Remember: ## c=flambda##
Therefore: ## f=c/lambda##
Here ##c## is the speed of light in a vacuum.
So:
As wavelength decreases frequency increases and as ##E=hf## where ##h## is constant (Planck’s constant) so does the energy that the waves carry. Waves with a short wavelength have the most energy.
Red waves have a relatively long wavelength (in the 700 nm range) and violet waves are much shorter – roughly half that.
Because violet waves have the shortest wavelength of the visible light spectrum they carry the most energy.