颜 attaches 彦 'refined' to 页, the head: originally the space between the eyebrows, then the whole face. Color came later — the face is where color shows first, in blushes and pallor.
颜色 is color, the word behind every paint chart and crayon box. 颜 as face survives in 颜值 'face-value' — internet slang for how good-looking someone is, scored like a stock. The classical 红颜 'rosy face' meant a beautiful woman.
The face 页 where every COLOR shows first.
颜值 'appearance index' turned beauty into a number — 颜值高 'high face-value' is modern China's compliment of choice, equal parts flattery and stock ticker.