Obama - Law
Bush - Business
Clinton - Law
Bush - Business
Reagan - Actor
Carter - Nuclear Engineer & Farmer
Ford - Law
Nixon - Law
LBJ - HS Teacher
JFK - Econ
Ike - Military
Truman - No degree
FDR - Law
Hoover - Engineer
Coolidge - Law
Harding - Journalist
Wilson - Law Prof
Taft - Law
Teddy Roosevelt - History & Politics
Law is clearly the modal occupation for presidents, but there's some diversity.