To do something like this is a non-trival feat. Part of the problem is the dynamic nature of a dashboard, and the code behind the scenes. Some visualizations will work, others will not. Splunk does not have that functionality to print a PDF from Django.
HOWEVER, if you were to re-create the dashboard in Simple XML, you would have the option to save as a PDF. HTML and Advanced XML cannot be saved as PDF natively..
Moving forward, ditch the Django, and go Simple XML or HTML.