Rinse tomatoes and cut into thick slices. Cut mozzarella into slices. Pluck the basil leaves from the stems. Remove seeds from the cantaloupe and cut into slices. Rinse arugula, shake dry and remove hard stalks if necessary. Rinse peppers and cut into rings. Drain squid.
Layer the tomato and mozzarella on 4 plates, season with salt and pepper, then drizzle with olive oil and sprinkle with basil. Place the prosciutto, olives, arugula, melon, squid and peppers around the tomato and mozzarella in a decorative manner.