A lot of people have used thinned silicone adhesives for coating, bonding, and laminating silnylon. There are a few old threads in this forum about that. Silicone adhesives are available in many colors, including some that are pretty opaque. You could just thin these with mineral spirits or hexane and paint it over a stencil.
Be aware that some silicone adhesives don't always cure well. I'm not sure why. I've had GE Silicone II cure poorly twice, and I had to scrape it off and try another brand (which worked great). It also happened with Permatex once. If it cures well, it will adhere strongly to the silnylon. Non-silicone adhesives or paints won't.
I've also applied thinned silicone adhesive to silnylon with an airbrush with good results. It remains a bit "tacky" after it cures. I tried silicone-based spray paint (high-temp stove paint) and it peeled off.
Post your results if you find something that works for you.