Multicolored smoke

Hey there, im doing smoke with this tutorial.

But i wish to have multicolored smoke.
So i put color ramp where in both color slots and then a gradient texture behind there to get all colors. But it doesent work right. Its still one color in the inside and one at the outside.

You know, you should post what you got (scene file, screenshot of settings, rendered image…) and what you wish to achieve (image reference: photo, concept sketch, illustration…).