Duncan Mills from Product Management became the go-to expert for ADF Faces Data Visualization Tools (DVT) Diagrammer matters. Duncan put together a yet 11 part tutorial that he released on the DVT product blog. Below is the complete list of links to all 11 documents for your and mine easy and convenient access
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part1
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part2
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part3
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part4
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part5
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part6
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part7
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part8
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part9
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part10
https://blogs.oracle.com/data-visualizations/entry/a_guide_to_diagram_part11
Frank