It doesn’t seem like you can make the nodes glow. According to the obsidian documentation, the graph view doesn’t actually use CSS. It uses WebGL, and Obsidian translates the CSS from themes into code for the graph view to use.
You should look at this post where they used CSS to kind of make the graph view beautiful-looking. Besides that, though, I think changing the colors and choosing a theme is the best you can do. Themes go a long way in making Obsidian look pretty.
Since you mentioned themes, I assume you already know where to find and change them, but in case you don’t, it’s in Settings > Appearance > Themes.