I use these settings and styles to draw diagrams that look like this:
The libraries include shapes and more complex arrangements to quickly draw diagrams like one shown in the example.
Head over to https://www.lasssim.com/diagrams/ to find a button that will redirect you to a preconfigured diagrams.net editor with these styles and settings.
You can download the desktop application at https://www.diagrams.net/blog/diagrams-offline
Paste the contents of styles.json into the configuration box that will pop up when you click the menu item shown in the screenshot above (Extras -> Configuration).
Clone this repository and open the libraries from the lib/ directory via File -> Open Library...
- Fork the repository
- Make changes to the json files with your favorite editor
- Make changes to the libraries using the standalone editor (described above)
- Submit a Pull Request