I actually use Grafana for graphing all kinds of data, including countless server statistics like CPU utilization, mail query size or HDD temperature. By installing the whole “TICK” stack, you can collect, visualize and notify status data.
I want to maintain snippets and examples here in the forum. There is never one RIGHT solution and problems might occur on other systems. Users should be allowed to ask questions or propose improvements. The tagging and sorting/filtering system of discourse will ensure some management.
Regarding tutorials, they should also for now be posted in the forum, I might like to adopt some to the docs as soon as they hit a certain amount of maturity.
Good point. I’ll open a new thread to organize the transition when the time is right. Time is the limiting factor 
Just a random thought: can you create a rule that runs each midnight, generates the graph and saves it as a static image? Just add that image to the sitemap. I am guessing it does not need to be interactive.
May be its will work. But how using rules copy image?
Sorry, I am also just a beginner in OH. The answer is most probably in a pyhton script. You just use the rule to execute it once a day (actually it can also be a simple cron job).
Something like this: http://stackoverflow.com/questions/13137817/how-to-download-image-using-requests
Good idea. This should be possible by creating a cron job (linux cron, not openhab rule) at midnight with the following content:
wget -O /etc/openhab2/html/daily-graph.png http://myopenhabsystem:8080/path-to/graph-to-download.png
This should save the graph at midnight to the static content folder which in return is available at http://myopenhabsystem:8080/static/daily-graph.png hence can be displayed with a sitemap image element.
Thanks to @ThomDietrich’s great write-up:
InfluxDB+Grafana persistence and graphing
You could switch to InfluxDB + Grafana. It lets you surviving a relative begin and end date in the graph URL.
begin=now-2d&end=now-1