In spoken Engpsh, you can say "group photo" or "team photo" to refer to a photo of a group of people. You can also simply say "let's take a photo" or "can we take a photo together?" if you want to suggest taking a photo with a group of people. If you want to specifically ask someone to take a photo for you, you can say "could you take a photo for us?" or "would you mind taking a photo for us?"