Don't spray the colour on. It is much easier to just apply window tinting films to achieve full unimpaired visibility. Most other methods create a haze on the visor you will have to see through. Colour tint on the outside and mirror tint on the inside will only slightly darken what you see and colourise it, no avoiding that but its a better solution then loosing visibility to paint particulates on the visor
I do my visors like that. Halo 3 visor didn't have any hexagon, so have it even easier.
Make a fitting form. Then buy a car light tinted film, best orange or orange+yellow and one-way-mirror-film used either for cars or windows. Cost? around 5$?