Sorry man, I do not believe there are any makers of pre-printed decals. Everyone I now who has replicated the image (be it on 1:1 armor, wood plaques, or even on guitars) has had to free hand paint it.
I take it you are looking for a 1:1 image for your own armor? If you don't feel comfortable having a go at it yourself, it might be worth popping over to the Aliens Legacy forum and seeing if there is anyone near you who could paint it up.