It doesn't produce these itself, but instead relies on a number of plugins which are responsible for gathering the data they require, and describing how this should be graphed. In fact, it does little more than fielding requests from the Munin master, running the appropriate plugins, and returning the output they produce.
/etc/munin/munin-node.conf /etc/munin/plugins/* /etc/munin/plugin-conf.d/* /var/run/munin/munin-sched.pid /var/log/munin/munin-sched.log
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
This program is released under the GNU General Public License
Many plugins can report whether or not they can reasonably be used on the node. "munin-node-configure" can use this information to help manage installed plugins.
The network protocol is documented at <http://munin-monitoring.org/wiki/network-protocol>