Not quite sure what you mean or why you'd want to see all modified files by a running service. Tools like Tripwire
can be used to scan your system and keep a snapshot of all files and then report back on modified files the next time it is ran but this picks up everything, not just those modified by a particular service.
You could write a bash script that checks for modified files based on the last modified date, but again, it wouldn't do it for a particular service that I know of. Just depends on what you're wanting this information for.