I don't think there's a log you can print but you can do the following. Not quite what you want, but better than nothing...
You need to set the fax confirmation option to log faxes before you send anything. The default option is off, so you won't be able to get a fax log for anything you've already sent unfortunately.
1. Press Setup
2. Press 2 then press 1. This displays the Print Report menu
3. Select Fax Confirmation
to highlight one of the following, then press OK
Does not print a fax confirmation report when you send and receive faxes successfully. This is the default setting.
On Fax Send
Prints a fax confirmation report for every fax you send.
On Fax Receive
Prints a fax confirmation report for every fax you receive.
Send & Receive
Prints a fax confirmation report for every fax you send and receive.