The color settings is the sub section under the theme section dedicated to decide which color you want to see at various places on your website and mobile app.
There are plenty of options that helps you control the color using multiple fields from Mobile header to check out background and doing it is quite easy. Simply click here to choose the color.
In a similar manner color of 'Text', 'Buttons', 'Driver App' and 'Merchant App' can be determined from here, after choosing the right color all you need is to click on the save.