Hey there! Do you have root access to the server, or just access to the one cPanel account in question? Although the lines aren't on the hour, it does look to be hourly, which could be caused by a cron, if this traffic is showing outbound data.
If this is inbound data, you'll want to check the cPanel >> Raw Access Logs chart and review those logs to see if you can identify any patterns there. I know that is just "checking the logs" but unfortunately there isn't going to be an easier solution available.