Here are some English idioms connected with colors.
1. WHITE ELEPHANT
meaning: something that is useless for us and costs money to get it or to maintain.
example: This new gallery is a white elephant, nobody visits it.
meaning: very shy, cowardly, not brave
example: My colleague is yellow-bellied, he will never talk to his boss.
3. GREEN WITH ENVY
meaning: to be very jealous
example: She was green with envy when she saw her boyfriend with another girl.
4. OUT OF THE BLUE
example: It was calm evening but then, out of the blue I heard some loud noise.
5. PAINT THE TOWN RED
meaning: have a good time, party or go out
example: Every weekend we go out and paint the town red.
6. TALK A BLUE STREAK
meaning: to talk quickly and a lot
example: I can’t stand the girls who talk a blue streak. I have a headache after such conversations.
7. BLACK SHEEP
meaning: unpleasant or bad person of a group
example: He was a black sheep in our class, nobody liked him.
8. A GREY AREA
meaning: something that is without clear rules and people don’t know how to deal with it
example: I am good at chemistry and math, but physics is a grey area for me.
9. SEE RED
meaning: to be very angry
example: Alice saw red because she failed her important exam.
10. IN THE BLACK
meaning: to be successsful or not in debt
example: Their company is in the black, they will earn more money.