I’ve added a feature request as a to-do on the github page. I’m planning to re-structure the way it gets data at some point and will probably refactor it at that time. I do have it sorting by name, then again by capability at this point, so all the capabilities are grouped together.
If you want multiple headings for now, you’d need to run copies of the modules. To do this, clone the github project and rename the folder. You also would need to update the file names/references from MMM-Smartthings to something like MMM-Smartthings-switches for example. Also update the module name reference in the renamed MMM-Smartthings-XXXXX.js to the new module name. Just add another module block in your config.js with the newly renamed module and it will run an additional instance. You may want to delete the .git directory within the copies to prevent any auto-update scripts from reverting changes.
Just keep in mind that the number of requests to Smartthings is about 250 a minute per device/application, so you may need to generate a separate key, depending on the number of devices and frequency of updates, to keep from being throttled by Smartthings.