Virginia,
You can show this data in a Report by choosing the information but it will show it as a spreadsheet (not graph). Currently this is not available within the Reports Module but we have a new version currently being worked on that will have more capabilities and will include Dashboards as well that will allow you to easily choose the data and how you want it presented. We do not have a firm date for this release but it is expected in Q1 2015, maybe February.
Currently, the way to show this in a Graph format is to create a View in the Task Module and use Chart instead of Grid. Select the type of Chart you want and add the fields you wish to use for X and Y axis. This should give you what you want.
Sincerely,
Boris