How can I make my tomato-herb pasta sauce a lighter color?
Maybe too much basil, depending on how much you are using.  It really only takes a couple of leaves to add flavor, if you are using fresh.  I would not recommend dried.  You are probably also getting color from the dried pasilla pepper.  You could leave that out.  If you want a hit of pepper, add some to your final presentation. Cooking time will also effect the color of a tomato sauce.  Try cooking for a shorter time.  My basic tomato sauce cooks for 20 - 30 minutes.