The Noir theme comes with the ability to alter the accent color with a single color picker button right in the Customizer. But you can also alter every color aspect of the theme via the advanced styling settings.
Accent Color Picker
Simply browser to Appearance > Customize > Styling > Main and here you can select the accent color of your choice. You can easily make the theme unique to match your personal style!
Advanced Styling Options
To truly make the Noir theme your own, you can make use of all the various styling options to alter the color of your header, menu, links, body text, sidebar, footer, etc!