I think you have to create a table/matrix outside the graph itself, however, there are some neat ways of making it correspond to the chart (like a legend) and even making it interactive at these links:

Custom chart legend:

http://blogs.msdn.com/b/bwelcker/archive/2005/05/20/perfect-from-now-on-custom-chart-legends.aspx

Add a data table (ctrl+f for Adding Chart Data Tables):

http://msdn.microsoft.com/en-us/library/aa964128(v=sql.90).aspx#moressrscharts_topic4