To control the display order of your product groups, a simple naming convention can be used. Prefix your "group names" with numbers to sequence them. For example, to display 'Group 3' first, 'Group 1' second, and 'Group 2' last, rename your groups to:
01 - Group 3
02 - Group 1
03 - Group 2
This numbering prefix will sort the groups in the order you desire on the product page.
Note: It's the "Group Name" you need to add the prefix to, and not the "Option Name".