Why do you suppose that Death saw life in terms of color and reffered to color in terms of taste?

Colour supports much of how Death views the world. Death sees the souls of people in terms of colour in the sky. Colour begins to define Death's sense of understanding of his job in a very chaotic world,

“People observe the colors of a day only at its beginnings and ends, but to me it's quite clear that a day merges through a multitude of shades and intonations with each passing moment. A single hour can consist of thousands of different colors. Waxy yellows, cloud-spot blues. Murky darkness. In my line of work, I make it a point to notice them.”

Colour enables death to distance himself from the personal experiences of each character and see humanity as a whole, as a kaleidoscope of pleasure and pain, the sacred and profane. Giving tastes to these colours in the context of the book is difficult. The book is so morbid and we are essentially dealing with the essence of people, their souls if you will.