"In graduate programs" versus "at graduate level"
Solution 1:
I think Courses taken at graduate level is more appropriate since it will imply that you are referring to all the courses you have pursued while in graduate program(s).
On the other hand, Courses taken in graduate program would limit the clarity and one may end up assuming that you did only one graduate program.
On you can say Courses pursued in graduate programs, but the first one seems more appropriate to me.
Thanks.
Solution 2:
Firstly, "courses taken at graduate level" just about sounds perfect. It also removes the need to pinpoint any specific program that was taken.
"courses taken at graduate program", on the other hand should ideally be followed by the name of the program. This should be used only in the event that you have taken multiple programs at graduate level and is redundant otherwise.
Solution 3:
You could just sum it up as
Post-graduate courses
or
Post-graduate course work
or
Post-graduate studies