How to setup colors for your next Joomla4 website is explained here.
First off, we have made a great effort to make things easy for you. So you do not have to setup tons of colors to change the look of your website, but just a couple of them. And even then you have the option to custom-css all you want with our custom-css option, explained here.
Having said that, changing the colors is quite simple. Just go to the module, select the tab colors to get you going. Here you can setup all the main colors, like primary, link, hover, footer background, card header, card header text badge, and badge text.
When going into General you have even more options:
Some colors are hex colors for instance #ffffff, and others ar RGBA. The latter allows you to work with transparency. This is a great feature to for instance have a background-image slightly visible underneath your content.
The header section has it's own color options, also available in KickstartCassiopeia:
By using more instances of the module, you can change the color scheme on your existing website, creating custom sections that have their own colorsets. How this is done can be read here.