Didn't work for me. when i put in with a GetKeyUp code it only turns white HELP

Colors are not 0-255 unless you use the Color32 class.

@DzjengisKhan: Don't ask questions as an ANSWER to this question. Answers should answer the question. Use "add new comment" if you want to clarify something.

Beside that, yes you're right, It will most the time return a white color because the Color struct uses values between 0.0 and 1.0

To use byte color values you can use the Color32 struct which converts automatically into a Color struct.

So either use:

// C#
particle.color = new Color(Random.Range(0.0f, 1.0f), Random.Range(0.0f, 1.0f), Random.Range(0.0f, 1.0f), 1.0f);
// UnityScript
particle.color = Color(Random.Range(0.0, 1.0), Random.Range(0.0, 1.0), Random.Range(0.0, 1.0), 1.0);

or

// C#
particle.color = new Color32(Random.Range(0, 255), Random.Range(0, 255), Random.Range(0, 255), 1);

// UnityScript
particle.color = Color32(Random.Range(0, 255), Random.Range(0, 255), Random.Range(0, 255), 255);

I've fixed the answer ;)