When you say files/paths "at a domain", in general you have a misunderstanding. A domain is basically a name that points to a resource see here.
If this sounds kind of vague, it's because it is. Multiple computers can host a domain (ie. serve up resources for the same domain), and the resources they serve up don't have to be files at all. You can point your browser at http:// somesite/somefile.html, and that "somefile.html" may not exist at all (yet the site could still return a webpage).
You can't (in general) list all the files/paths at a "domain", but if you have access, you can certainly do that for one or more computers. Certain websites may provide a way to get a directory listing, but even then it would just be from the "DocumentRoot" (in Apache terms) of the website (not from root).
EDIT: IF your domain is hosted on a single computer, and you have full access through ftp, you could use something like the python script in the answer here to get a remote directory listing (of this computer). You probably need to change the line that says this:
ftp.login()
to this:
ftp.login(user='your username', passwd='your password')
While it may seem like the same thing, what you're really asking for is a remote directory listing of a computer, not a domain (even if a dns lookup resolves your domain to a computer).