You don't "need" to do any extra reading. Your universities should provide some sort of reading list (and you're not supposed to read all of those books either), but look at those as inspiration.
If you're trying to write a personal statement, perhaps find a book on a topic you're interested in, but it is really not the deciding factor in your application - You need to write about what you've done which relates to the course. Explain why you're the right candidate for them and how you've done research which is appropriate. Just reading is not going to be enough (you need to be more than just "interested").
Technology magazines and books from the library may help, but find opportunities to apply "engineering skills" to what you're currently doing as that will have a far greater weight in your application.