You don't. Directors do not of themselves decide to make a movie. This is decided by the studios. The studios will then usually approach directors to see if they want to direct said movie, based on the script.
Basically because they're the ones that have to put up the money to make a movie. Since movies cost many, many millions of dollars to make they are not unsurprisingly cautious about turning any book into a moving picture.
Yes you can approach directors, but since they usually make their decisions based on movie scripts. In general, they won't interested in reading every book that comes their way before deciding to make a movie out of it. Certainly some directors do decide to make a movie based on a book they have read. These directors may also write the script for their own movies. They still have to go to the studios to get the money raised.
Sadly it looks unprofessional for a writer to approach a movie director and say I have written a book and I'd like you to make a movie based on it. Being unprofessional will kill the project stone dead before it gets out the door.
Being professional, you should either write your own movie script based on your book and join the Hollywood scriptwriters' guild or possibly approach a script writer who can determine if your book (a) can be made into a movie script, and (b) is even worth being turned into a movie script. Basically a book by itself won't sell its way into becoming a movie. Someone has to write that script.
Next you will need an agent to hawk your script around the studios and even to movie directors and producers. never forget about producers, they're the money people behind the scenes. Having an agent is professional, without one you will get nowhere.
Remember you are competing against battalions of other hopeful writers who believe, usually wrongly, that if they can approach a movie director it will get their book, magically, transformed into a movie. That might happen in a movie, this is reality.
Oh, yes, there is one way you can get your book made into a Hollywood movie. Write a bestseller that sells millions and which by its very nature demands that it should be made into a movie. Then the movie people will come to you. So write the best book you can and hope it's pure gold movie material.
Forget about chasing Hollywood directors. Find out everything you can about the movie industry. Write your movie script. Join the screenwriters' guild. Be professional always. Hire an agent. But first write the best book ever.