My biggest advice regarding flavor would be to strain out all the solids at the end and reduce the broth by about one-third. Take a look at my homemade chicken stock recipe for guidelines. While the soup is reducing, you can bone the chicken and return the pieces to the broth along with whatever vegetables you want to have in the final soup. To give the flavor a head start, you can sauté the vegetables in the stock pot in a mixture of olive oil and butter before adding the chicken and water. You can also roast the vegetables in a medium oven for about 30 minutes before starting the soup. Be sure to deglaze the roasting pan with water and add it to the soup. As for the color, stop worrying about it. Precooking the vegetables and having some carrots in the mix will help the color a bit, but it really isn’t important.