I have found the 12 round schedule below by computer search and I think it should work. You have the option of shortening the tournament by playing (9 v 10) on the 5th court in round 11.
C1 C2 C3 C4 byes
(1 9) (2 6) (3 10) (4 5) (7 8)
(1 5) (2 3) (6 10) (7 8) (4 9)
(1 10) (2 5) (3 8) (4 9) (6 7)
(1 8) (2 4) (5 10) (6 7) (3 9)
(1 7) (2 8) (3 9) (4 10) (5 6)
(1 3) (2 9) (4 7) (5 6) (8 10)
(3 4) (5 7) (6 9) (8 10) (1 2)
(1 2) (4 6) (7 10) (8 9) (3 5)
(1 6) (3 5) (4 8) (7 9) (2 10)
(2 10) (3 7) (5 9) (6 8) (1 4)
(1 4) (2 7) (3 6) (5 8) (9 10)
(9 10)