Put the chicken in a large bowl; add in pineapple, grapes, and mango (if you are not serving right away, cover and refrigerate for up to 2 hours; if you refrigerate longer, the pineapple tends to give off its juices).
To make the dressing: whisk the mayonnaise, orange juice, and zest together in a small bowl.
Stir in 1/4 cup nuts.
Pour the dressing over the chicken mixture; toss gently but thoroughly.
Peel the papaya, using a vegetable peeler.
Cut it in half, remove the seeds, and the cut it vertically into even slices.
Line individual plates with lettuce leaves; mound the chicken salad in the middle of the plate; arrange papaya slices around the salad along with a cluster of grapes.