Sounds like you need to have a discussion with him. He also sent it to you to allow you to review it. Maybe you should just take a bomb to it and blow it up. Haha, but what I mean is to litterally scrap it and write it for him.
I know its tough, but this is your life, not his. Many times recommenders are way out of the loop and have a challenging time writing these letters. Just remember, as long as he has good things to say about you, you should be fine. They understand that recommenders are busy, not professional writers, and won't all be the same. Buuut, if it is truly awful, it will look like he didn't take the necessary time for you.
It might just make the most sense to rewrite, or really revise his copy to make it what you want. Use his words, structure, etc... but change a bunch to make it more what you want. If he's a cool boss, he will submit what you give back to him no questions asked. Just tell him that the format they expect was slightly different then what he had.