I was under the impression that they were talking about the water sample puzzle; the only puzzle in the game I would consider a "graph" puzzle is that one since you move the lines on the graph to make them match up. If you read the file on the puzzle it explains it, even if simply - all you do is match up the lines correctly and then test the water. *shrugs* I never understood what the big deal was.
The only ones I found challenging were the music box puzzle and that's because, after a few tries, all the notes started to sound the same to me - I get it on the first try everytime now, though; I guess it was just that first run-through that I had a problem with it - and the past, present and future puzzle with the amber, obsidian and crystal orbs. (I still have problems with that one.)
Oh, it had gotten a bit off topic, as in onto another puzzle that was a problem I think.
Yeah, the water sample one though, it was simple, as you just had to match it up. That doesn't mean it didn't take a long time though....
The one with the 3 stones is certainly my least favorite. I've really been hoping to find a good consistent way to do that puzzle, so that I don't have to mess with it for so long each time.
Have you figured it out, or is it still guess & check with you too?