The false colouring is mainly due to the fact that they are using beams of electrons, not visible light. But a typical virus is ~100nm ( https://book.bionumbers

The false colouring is mainly due to the fact that they are using beams of electrons, not visible light. But a typical virus is ~100nm ( https://book.bionumbers.org/how-big-are-viruses/ https://book.bionumbers.org/how-big-are-viruses/ ) and the wave length of green light ~500 nm. So I guess it isn't really meaningful to ask 'what colour is a virus'.