No where, you can search for the answer online, which is also available on Yahoo answers, and the answerer says this site: http://www.zarosaki.com/
but really not all the lastest manga is available there. One Manga (http://www.onemanga.com/Naruto/) is the most popular manga site. And manga here is all in BLACK AND WHITE!
+ Note this: Youtube has many Naruto episodes in colour, by episode 'mean many lastest manga episodes.