what is that color mode called.. in cameras..?

Oil, paint, acrylic paint, oil pastels, or even colored pencils are used to selectively color areas of a black and white print, or to color the whole image.

Here is a great website with a step by step guide and a list of the supplies you will need:

http://nc.essortment.com/handcolorblack_rqnq.htm

Of course this can be done easily with photoshop, but the results are often too obvious and you lose the lovely tones and depth. Oil paint on black and white fiber based matte medium paper is my favorite way to selectively color an image.

No camera currently in existence can do what you ask. You must post process a color image with image editting software. Hand coloring was done in the days of film.

My experience is that they take a B&W picture and colorize it by hand, actually now they do it digitally with photoshop and an Cintique tablet...