Take a look at document templates: How To: Create and build a document template
After you have built a template, you can use a microflow to create a System.FileDocument, then use a GenerateDocuemnt action to create a document from your document template and save it to the new FileDocument object, then display it using a Download action
For graphical reports, take a look in the AppStore (search for reports) like Simple Charts or Fusion Charts
Thanks David