Having had to do that quite a few time, for instance for audio / control / visuals graphs in https://ossia.io as well as some proprietary stuff, I'm pretty much convinced now that it's easier to just whip up the graph data structure that fits the problem rather than trying to make a generic framework for that. Every time I tried to use a library of dataflow nodes it ended up not doing what I wanted the way I wanted, and rewriting something tailored to the use case was just much faster especially considering that you likely want user interface features which will be specific to what you are doing with your dataflow graph.