to change color (of leaves in autumn); to turn red; to turn yellow
to ripen (and change color)
to become sexually aware; to reach puberty
山の木々が色付き始めた。
The trees on the mountain have begun to change color.
庭の柿が赤く色付いた。
The persimmons in the garden ripened to red.
秋が深まると葉が美しく色付く景色が広がる。
As autumn deepens, a landscape of beautifully coloured leaves spreads out.