Hey nikander,
That's correct, there are no visuals.
Justine found them all afaik without them having any sort of graphics but I don't know how long it took her. The initial design wasn't intended to have players just search for them (like with some of the hidden item missions) but to come upon them naturally while doing some of the other missions on Cyrene.
That being said, I do think that this mission could be improved, namely the objectives could be shown and not hidden, seeing the names might really help to nail down where the rifts are at.
If you think it will help I can list them in this thread.
Cheers,
Kris