The four colours attributed to the functions are based on certain feeling values.
Feeling is red, this is connected with blood and fire, with passion and love which is supposed to be warm and glowing.
Sensation is green, this is connected with the earth and perceiving reality.
Thinking is white, or blue, cold like snow and Intuition is gold or yellow because it is felt to shine and radiate.
You can see this in an intuitive person’s eyes, in the picture of Goethe by Stieler, for instance.
Such eyes do not look at things, they gleam towards them; they see no detail but rather a sort of magic atmosphere round things, an inner perception rather than an outer.
But if you are going to look down a microscope it is useless to gleam in its direction, you need sensation eyes for that, pincette eyes, which will pick out every detail. ~Carl Jung, ETH Lecture, 10Feb1939