Here is the code of neovis.js which i use in my code to display the neo4j output.
However, I want to implement something with the colors. That is why i want to know what defines / what variable defines the colors that the nodes in neovis.js display in its javascript counterpart.
That's a good question. I haven't made much use of neovis but have you tried maybe changing the colors in your neo4j desktop and seeing if you get a change in your neovis representation? That's the first thing that pops into my head.
For every label that you define under label, there is a community property where you can define a property used for coloring nodes. For example, assume there is a node label User, every user has a gender property, and your goal is to color every gender differently: