Not many SharePoint administrators have the good fortune to be administering a site with only a few sub-sites or groups. Most administrators have to manage dozens or hundreds of different sites and permission groups.
By default SharePoint displays all the groups alphabetically, in ascending order. From here, you can change the sort order or apply a filter, which does not make group management very easy.
1. Navigate to "People and Groups" for the site collection
2. Click "Groups" to show all groups
3. Find the group you want to modify and click the edit icon
4. In the group name, just add an underscore and number to the front
I strongly suggest putting an underscore "_" as the very first character. That way, if someone creates another group that begins with a number, such as a date, your groups will still show up at the top.
I also suggest maintaining a numbering convention where the least significant bits represent the particular membership group:
1 = Owners
2 = Members
3 = Visitors
If the organization is small, you could get away with a 2-3 digit numbering scheme. (_01, _002, etc)
If it’s very large or multi-national, I suggest at least 4 digits, with the most significant bits representing a particular country or region. That way you can clearly separate one side from another, and still have room for growth.