Saints manager Tommy Wright had hoped to sign Graham on a permanent deal but Ross County announced on Thursday he would be a Staggies player next season.
Defender Brian Easton has shrugged off a knock and striker Steven MacLean has recovered from a bruise around his eye.
Meanwhile, Ryan McGowan has joined Dundee United’s absentee list ahead of the game.
The defender suffered a thigh injury against Inverness on Tuesday and will miss the last three games of the season.
Ryan Dow (groin), Paul Paton (knee) and Mario Bilate (hamstring) are also out for the campaign.