The theme comes with an easy to use skin color's customization panel. While this panel allows you to easily change the colors of the skin. It is always recommended that modifications to the css of the theme are applied trough a child theme. This is much better in terms of coding performances.
To enable the custom skin, navigate to the Theme Options panel section called "Skin Settings". Make sure you enable the option "Enable Custom Skin", once enabled you can feel free to change the colors of the skin.