On HP ALM 11
Go to Test Lab, select the folder that you want to generate graph for.
At your right you will see a pane with Live Analysis hyperlink. Click on that which will open up a small window with various filter options.
Select on X axis the field that has your tester details e.g. responsible tester or test designer, etc.
On Y axis choose your required field like Status for test runs/cases
and then click next.
Thats it your graph will be ready.
Alternatively you can also use Analysis on the menu bar or can also use Management Module.
All the best!