So, color vision depends on the cones. Notice that light itself has no color. Light rays differ from one another by wavelength . Color exists only in conscious minds. It is a nervous system's way of telling one wavelength from another.
Color vision is simply a way of discriminating wavelengths.
We have this ability because there are so many objects in the environment that do not reflect back all of the wavelengths that come to them from the sun. They absorb some and reflect back the rest. The rods and cones respond by converting light energy into neural currents that act at the receptor-bipolar synapse to release transmitter. The bipolars, in turn, stimulate the ganglion cells, and fire their axons. Thus, the image goes through the retina in one direction and the information-carrying electrical currents go through it in the opposite direction.