Is there a certain color to which a woman has to adhere in her Hijaab, and by this I mean the head cover? Is it obligatory that the head cover should cover the whole area of the chest? What is the Islamic ruling on colored Hijaab that, despite their color, cover the whole body and conform to the Islamic dress code?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

It is not a condition for the Hijab to have a certain color, nor should any part of it be of a single color. However, it should not be an adornment in itself and should not attract the gaze of men. Accordingly, if it is an adornment in itself, then it is not allowed to be worn and cannot be called Hijab because the Hijab is what prevents adornments to appear to non-Mahram (permanently unmarriageable kin) men.

The Hijab must cover all the body along with the face and palms  according to the scholars' most valid opinion.

Allaah Knows best.