Wow, that would be an ambitious project. It sounds like you want to do it as a learning exercise. You could learn a lot but it will take a lot of work. As a wild guess, maybe 4000 hours.
There are two ways to go. Method 1 is to get some books on GUI design. X Windows was open source from the start, there should e lots of chat and docs online. The disadvantage is that it poisons your mind, and you wind up with a X Windows look alike. I'm sure there are other documented GUIs out there.
Method two is to do it without reference to literature. You are likely to fail and have to start over more than once. But the learning will be more profound. We learn best from our own mistakes.
So, which is most important to you, getting to the end result, or the learning?
There are many gui packages, but I'm not up to date on them. For example Tk can be interfaced to C (I use it from Perl quite often). There are probably better, more modern choices, like Qt or something. Will GTK run on the arduino?