three bean salad recipe

1 can (15 oz) green beans, drained and rinsed 1 can (15 oz) yellow wax beans, drained and rinsed 1 can (15 oz) kidney beans, drained and rinsed 1 small red onion, finely chopped 1/2 cup chopped green bell pepper 1/2 cup chopped red bell pepper For the Dressing: 1/2 cup apple cider vinegar 1/3 cup granulated sugar 1/4 cup olive oil