sign of remorse; indication of regret
Used when someone's expression, attitude, or behavior shows they feel sorry for what they did. Often appears in negative contexts like 反省の色がない (shows no sign of remorse).
He showed no sign of remorse at all.
It was an attitude that showed no indication of regret.
Compound of 反省 (remorse, reflection) + の (possessive particle) + 色 (color, sign). The expression is transparent from its components.