If you are talking about sub-atomic particles, then the question does not necessarily apply! Due to the different scale of sub-atomic particle and the frequency of visible light (and what we perceive as colours), they have no colour because light cannot interact with them.
In particle physics, there is a property of certain elementary particles (called quarks and gluons) that is related to the particles’ strong interactions in the theory of quantum chromodynamics (QCD): this is called colour but is completely unrelated to visual perception of color.
We see colour based on what frequency of light is reflected by an object. The colour of certain particles depends on what particles you are referring to. I suppose the answer to your question is that particles can be any colour. If there is a particular kind of particle you are curiousl about leave a comment below and we will find out what colour it is for you 🙂