To change the permissions for the CUPS log files (access log, page log, and error log), add or change the LogFilePerm directive in /etc/cups/cupsd.conf (CentOS 6 and earlier) or /etc/cups/cups/cups-files.conf (CentOS 7 and later) to the desired numeric permissions.
For instance, to let anyone read the log file, set.
Restart the CUPS service after making the above change.
The LogFilePerm directive sets the permissions for all log files written by the CUPS scheduler. When CUPS starts up, it uses the LogFilePerm setting to give the log files the permissions that LogFilePerm specifies.