City.jsx

class City extends Component {
  state = {
    active: false,
  }

  handleClick = () => (
    this.setState({
      active: !this.state.active,
    })
  )

  render() {
    const { active } = this.state
    const { name } = this.props
    const color = active ? '#F00' : '#000'
    const cityStyle = { color }

    return (
      <div style={cityStyle} onClick={this.handleClick}>
        {name}
      </div>
    )
  }
}