Chains need lubricant between the pins and rollers. A powdered lubricant like graphite would be difficult to get down there. Perhaps if you mixed graphite with a carrier solvent like mineral spirits or white gas you get it to flow in there.
Keep using the triflow but after you let it soak in to the rollers and pins wipe the outside of the chain as dry as you can and this should eliminate much of the mess. The outside does not need the lube.
If you really ride that thing off-road, unless you live in a very dry climate, tri-flow or graphite aint gonna cut it. You need a wet lube to stick to your chain, protect it, and keep it lubed in moist or wet conditions (puddles?) And its gonna get dirty. It just is, sorry. Invest in a chain cleaner and a gallon of Simple Green (I have a Pedros and a Park Tool cleaner, the Pedros works much better). Its a 3 minute process, use an old bike bottle to rinse off the solvent with water. You can buy bike wet lube for 3-4 dollars for a tiny bottle or you can buy a half gallon of the same stuff, bar lube for chainsaws for the same price from the auto parts or hardware store. It's very similar to phil wood lube, Ive used it on all of my bikes for several years now. Stays on really well in the wet, and its formulated for lubing chains. Just wipe it off really well like you should with any lube. And yes it gets black just like any other wet lube. But dry lube just doesnt work as well. A little more convenient maybe, but not as effective except maybe in very dry conditions with a lot of dust. And graphite wont get into your pins very well, or stay on your chain, or protect it from corrosion. Plus it will still make your leg black!