How I do it:

since its in 'red, green, blue, alpha' I just open paint.net, draw the color i want and note the rgb in the script. Since it can only go up to 1 in the script I divide it by 255 (you can do the same with the alpha).

So it does look like (which won't work)
in the beginning, and after dividing it (which will work)

Not everyone will agree with that way but I think that's the easiest way to do it.