Hi,
I'm not at my workstation right now so I can't answer your question directly but I will give you a hint.

In hypershade you can select your noise texture, at the top of the hypershade window there is an icon that allows you to show all the input, output, and input+output connections to your selection. Click that and you will have all the inputs for your noise, I'm not sure you can change the colors but my guess is yes.

I don't know if this is the best way to do a cloud in Maya, maybe someone else can answer this.