I have general advice from group job interview experiences. I can't say how relatable or applicable my experiences will be compared to your program interviews but I can offer my simple opinion on the matter.
In a group interview I feel that it's important to assert yourself & show that you have a voice & an opinion on matters brought to you. In a group you should be able to express your opinions, collaborate on meanings, & argue your point. You want to stand out so you should make yourself be heard, just like you would in a class where the teacher is a real stickler on participation points.
Obviously a good tactic would be to make sure you're well versed on mission statements/expected program outcomes, or anything else available that gives you insight/information about the program & it's goals. Know why you want to be a part of the program, know what's important to the school/program & why you're a good fit.
This may be pretty straight forward, but I think the best advice you could get, aside from the obvious (like be prepared to discuss interview topics/have answers for common questions), is to have a voice & try to present yourself in a way that shows you have ideas, you're capable of contributing to a team, you're a good fit for the program, & that you know what you want out of it all.
Also, try to have questions of your own. I feel like in interviews I've always stood out b/c most applicants are so intimidated by the process that they forget they're interviewing the school/job too. You should try to have some questions of your own to get a connection with the interviewers. At the least it will make you stand out in comparison to others who maybe didn't have any questions of their own & just answered what was asked of them.
Again it may be general, but it's been my experience with group interviews & it's always seemed to benefit me.