Slice the peaches in about 2 inch slices and toss with canola oil.
In a separate dish, season chicken breast with olive oil, salt, pepper, garlic and lemon juice.
Heat outdoor or indoor grill to about 375°F.
Grill peaches for about 2 minutes each side, until grill marks appear, and peaches are softened but not mushy. Set aside.
Next grill the chicken about 3-4 minutes each side, until cooked through.
Slice the chicken in strips or cubes and set aside.
For the dressing: Whisk olive oil, balsamic vinegar, mustard, honey, salt and pepper.
To assemble the salad: On a platter spread arugula, layer with grilled chicken, peaches, sliced onion and sprinkle chopped walnuts on top. Dress and serve.