Preheat oven to 350°.
To prepare dressing, combine first 5 ingredients in a small bowl, stirring well with a whisk.
To prepare salad, combine 1 tablespoon dressing, squash, and sweet potato in a medium bowl; toss well. Place squash mixture on jelly-roll pan or roasting pan in a single layer. Bake at 350° for 15 minutes. Add green beans and wax beans; bake an additional 10 minutes. Cool slightly. Combine squash mixture, remaining dressing, arugula, and remaining ingredients in a large bowl, and toss well.