Once this feature is rolled out you will simply need to
- right click/double tap on a tab
- select Add to new group
- Name the new group
- Keep or change the color of the group
Unfortunately as of now it does not appear that you can save the groups for later on, but you could always use Ctrl Shift T to bring them all back if you close the browser by mistake.
Of course future updates may reflect he ability to save these groups (fingers crossed).
If you would like to give this a look, you will need to add this "experiment" in Chrome flags by entering in chrome://flags/ typing in tab groups, enabling, and then relaunch Chrome.
Embedded below is a 1 minute and 40 second YouTube tutorial.