With thanks to @KassnerNora,
nxviz has a new feature! Now, it is possible to specify the data to use to colour edges. Previously, this was available in the API but was not working as I had not the time to implement it.
Now, with Nora's PR merged in, users can declare their edges to be coloured by some edge metadata key! In addition to that, Nora included a
seaborn colour palette that may be useful for drawing other edge colours. The API remains a declarative API, giving users an easy way to specify how they want rational graph plots to be made.
Thank you for the contribution, Nora!