I feel ya. But remember your users probably don't care. You are trying to convey information, and your diagram does so effectively. Everything else is sugar. But if you are dissatisfied then you could also take a look at code2flow.com which is very quick and easy to use. I'd be quite curious if it solves your issue. I suspect it will.
Eh, the point is avoid unnecessary work. If you have just one diagram, creating it by hand is not a problem. If you have 10 or 20, you want automation. Especially since you'll want to keep the diagram continually updated, maybe tweakable with different styles; editing all diagrams by hand every time for every colour change is arduous compared to just running a single command to re-render.
