Post a colored manga picture of a character depicting a different hair color than what was used in the anime.

akatsuki no yona. yona's hair shouldn't be pink. it should be red.(the girl with the sword)

Keigo Atobe from Prince of Tennis. He has light brown hair and blue eyes in the manga but in the anime he has purple-black hair and onyx eyes (later shown to actually be an extremely dark blue).

Ai shite night.
In the manga Yakko has blonde hair, in the anime - brown.

Chelsea's hair and eyes are colored as shown in this cover for Manga volume 6 of Akame Ga Kill, but both will be pink in her upcoming appearance in the Anime.

Fairy Tail

Wendy in her Dragon force,
her hair colour is usually blue, but only in this panel it is pink...