There are many useful expressions in English that are made with colors. Here are some of the idioms and their examples.
A grey area: (a situation that is not very clear)
I don’t understand her, she has a grey area in her life that I cannot see.
A white lie: (a lie that doesn’t hurt anybody)
He asked me something that I couldn’t tell the truth. I just told him a white lie.
Black and blue: (badly bruised)
I had an accident yesterday and my face became black and blue.
Out of blue: (without warning)
The bird hit the plane out of blue.
The golden boy: (a very popular man)
Jack is the golden boy of his office.
To blacklist someone: (to exclude someone from your life)
John is on my blacklist. I don’t want to do anything with him.
To show one’s true colors: (to reveal one’s real character; usually dishonesty)
She finally showed her true colors for everyone by firing Jane.
The grass is always greener on the other side: (the situation for others is always better from your own)
My mother always nags about the yard to my father. She thinks the grass is always greener on the other side.
Pitch black: (totally dark)
The room was pitch black. I couldn’t see a thing.
Black and white: (two opposite things)
Kate and her sister are like black and white. They can't-do anything together.
Black market: (trading in illegal goods)
He bought a very expensive mobile. I bet he could buy it cheaper on the black market.
Black sheep: (the odd and strange person in a group)
John is the black sheep in the class. He always does strange things.
In someone’s black books: (in disfavor with someone)
We all were in our boss’s black books because he always was angry with us.
Our team had to work hard to succeed but she was the off-color one.
To feel blue: (to feel sad or disappointed)
Everybody was enjoying the party except for Bill. He felt blue throughout the night.
To paint the town red: (to go out and enjoy oneself)
She got a raise at work and decided to paint the town red that night.
To black out: (to lose consciousness)
My mom was ok, but suddenly she had a blackout.
Hope these color idioms come handy to you.