Season the chicken liberally with salt and pepper and spray with Canola cooking spray. Cook on a 450 degree grill for 6 minutes on the first side and 5 minutes on the second. Be sure to temp the chicken to be sure it reads 165 degrees.
Let chicken rest for 5 minutes, slice width-wise into ¼ inch slices.
Cut squash, zucchini and red pepper in half lengthwise. Salt and pepper liberally and spray with canola cooking spray. Grill for 4 minutes on the first side and 2 minutes on the other side. Let rest for 5 minutes.
Slice squash and zucchini on the diagonal. Cut pepper into long one-inch wide slices and then cut each slice on the diagonal into ½ inch pieces.
Mix all the ingredients together for the vinaigrette dressing.
Place a bed of mixed greens on each plate, then layer on grilled veggies, onions, olives, and feta. Top with you grilled chicken slices and drizzle with the vinaigrette.