Hello, and thank you for your response.
For your information, parameter presets at the graph level can currently be displayed and selected in 'Preview' mode, in the graph 'Input Parameters' settings (see attached GIF).
Once a preset is selected, you can use the 'Apply' button to apply its parameters, else it will switch back when exiting 'Preview' mode.
Regarding user-created presets on the Source website, this feature is still under development, as is indicated by the 'Alpha' label on the 3D Viewer panel. Features and improvements are added regularly to the Source website and tools, so be on the lookout for those!
Feel free to get back to us if you need further assistance.
Best regards.
Luca Giarrizzo