Separate template/style for separate posts

I want to make separate style/template for separate posts from certain categories. For eg. My posts from category 1 should have a same layout and the layout of category 2 should be different.

How do I achieve this?
I have read http://codex.wordpress.org/Category_Templates page and it teaches about how to use the separate templates for separate categories right?

But what I want is separate styles for separate posts. I found out that the file single.php handles the layout for the posts. What I want is have separate single.php files for separate category posts.

Thanks
Ashish