Spray a grill or grill pan with cooking spray and heat to medium-high heat. Rub chicken breasts with olive oil. Combine cumin, salt and pepper and rub spice mixture evenly onto chicken breasts. Grill until grill marks have formed and chicken is cooked through, about 4-5 minutes per side. Remove from heat, let rest for 5 minutes, then slice into 1/2-inch thick slices. Serve over coleslaw, if desired.