Garnish the kabobs with thyme sprigs for an extra touch.
Soak wooden skewers in water 30 minutes to prevent burning.
Thread turkey, peppers, and onions alternately onto skewers. Sprinkle kabobs evenly with Cajun seasoning; lightly coat with cooking spray.
Grill kabobs, covered with grill lid, over medium heat (300° to 350°) 6 to 8 minutes on each side or until done. Garnish, if desired.