How does the repository network work?

Hey! I am doing research in school on differential privacy involving developer networks and had been looking in the functionality of github’s repository network as an example for my research. Github explained in this doc (Viewing a repository's network - GitHub Docs) how to find the repository network, but there is no key attach to explain, for example, what the different colors of the network lines mean? Can anyone help me to understand the repository network graph?

The colors are automatically generated and are just there to help try to distinguish different portions of the graph.

Consider Network Graph · actions/checkout · GitHub :

Sometimes you’ll see merges, and might want to trace the incoming line to the horizontal line. If everything was black, you’d be slightly more likely to lose track of things.