Does it make sense to rename this file?
From my perspective, the name of your file for the Site Map is of no importance. Now, when it comes to visitors, that's another story (the visible text link).
Since I've been using the term Site Map from the beginning (early 1996), I may be a little biased in this. I think the term Site Map gives the visitor a clear definition of where to find the mother of all pages.
Now, if you want to be creative and use a keyword rich link to the site map, you could. But, will the visitor understand what the link is? Does it convey the proper message? I believe the term Site Map is so ingrained in the general surfing public, that they may be looking for that link if they get lost on a site. A search function would eliminate most of the confusion but I still think Site Map is as self explanatory as you can get.
We are talking one link here. Why is it important to try and reinvent the wheel and throw in a keyword rich link which the general public may not fully understand. Again, if you are creative and can come up with something that is self explanatory, then more power to you.