You can do this through the Policy section --> login as Serveradmin ---> bottom right "Policies" you can configure the logo url there and so on.

Additionally you can make your own theme or overwrite the logo in default theme (copy over the default dir in app_themes and app_skins rename it to your theme (i would recommend to leave default for updates and so on).

then replace the logo / modify some of the css to your colors --> once done go to app_data --> SupportedThemes.config and add your theme to it 🙂

Benefit of your own controlled theme: it won't get overwritten by updates.

Downside of your own theme: you will need to process changes to the default theme to your own theme (like in v1.1.0 a major update will come out regarding design)