Did she just show up one day? Do you have any neighbors that may have lost her? Sleeping on your front porch isn't reall super safe for her...especially if she is alone. She definately looks like an easter egger...If I were you, I would ask around and see if any of my neighbors keep chickens, and see if they are missing her. One of our guineas was missing for two weeks before someone came and knocked on our door saying she had run into the next neighborhood over. We were able to find and catch her. We were so thrilled to have her home again...after that, if no one was missing her (and could PROVE she belonged to them), I would wait till she went to roost, grab her, put her in a carrier/crate, and either find her a home with a good sturdy coop and other companions, or get a good sturdy coop and some companions for her, and keep her myself. Actually, I would catch her FIRST, and keep her contained for a couple of weeks while looking for a potential owner.
She looks young, and very pretty. As others have stated, EEs have the potential to lay blue or green eggs.
My guess is EE as well, looks like a young hen. Where are you located? You may post in the area board and see if the owner happens to be a member here.