Because color is photons in a narrow range of wavelengths/energies visible to the human eye. Atoms have electrons that can emit and absorb photons under certain circumstances, but don’t have any intrinsic color themselves.
Color charge is a property of quarks thats trinary in nature, and is usually described in terms of red, green, and blue, since color is a useful analogy to how it functions. Despite the name, colored light and color charge are not actually related outside of the analogy.