essentially start by identifying the accounts posting links to the domain in question, then analyze the voting behavior of the accounts upvoting these posts. you can start by sorting out accounts that have legitimate activity and then narrow it down further and find common patterns that only apply to these accounts.
most of them were also created in similar time frames.
edit:
to extend on this, once you have something to go on with it's fairly easy. the hard part is finding something that applies in a more generic way to identify this happening before someone else discovers unusual voting patterns and reports them.
it was already shared in an admin coordination matrix room as well