This theme is based on the Material Design colors guidelines.

Relevant information about colors

1. Some colors are applied to multiple elements.
2. You can override global colors for specific sections as Menu Bar or Footer.
3. Page and Paper backgrounds must have high contrast with the Text color: it means you can’t use black page background and white paper background, as on one of those the text will be invisible.
4. This theme uses gradients for buttons or Headers. Each color of the gradient can be customized.
5. You should use a contrast or bright color for gradients and accent parts.
6. The Primary color should better be a tint that makes contrast with the Page Background
7. Some items as headers or post images can have a gradient overlay

On the customizer, go to Theme Customization -> Colors.

To save the changes, click Publish.

 

Some good resources: