I have no images on hand, but I am sure someone can go and screenshot some classic pictures of the worlds and their main features.
My original thoughts were to have a rectangular image divided into three sections next to each other by a diagonal line (or zigzag), but vertical lines or a space would be fine. We don't want to overdo the images, so the Twilight world could probably do without an image (or add it as a fourth section). If four sections then perhaps they can be quarters of the image.
The overall image can't be any larger than the ones seen on Hunger Games in Minecraft | Minecraft | TOG - The Older Gamers
(which are slightly larger than when displayed, and yes, I know that is bad form for a webpage). The smallest they would be half of the size of those on Minecraft | Minecraft | TOG - The Older Gamers