There should just be a larger arrow button on the left side of the skill that puts as many points into the skill as it can, limited by either SP or the skill cap.
But yeah, there's no faster way than just clicking. Some general advice, though:
1) Don't overclick, it gets tiring. Click only as fast or maybe slightly faster than the game will allow (which isn't very fast) 2) There's an "are you sure?" safety net for if you try to put SP in lower job skills when it can be used on higher job stuff. Max what you're 100% sure you need, then leave the dump points for later. No need to cross reference builds or count levels or anything. If you're playing a class that has separate SP pools, there's even less thinking involved. 3) Trying to finish everything all at once blows, just finish up your main and then fiddle with other chars when you have time. Few people play everything on their account all the time.