You can dynamically change skin of program. There are many skins created by professional designers are installed with CoolSpeaking, or available from the YesGoal website. It's even possible to make CoolSpeaking look like an application from other OS.
Steps to Install Skin:
Visit YesGoal Website to download skins and save skin-file to skins folder in CoolSpeaking's installation directory. (For example, if you installed CoolSpeaking in "C:\Program Files\CoolSpeaking", the skins folder will be "C:\Program Files\CoolSpeaking\skins".)
If you are using CoolSpeaking, restart it.
Choose "Skins" from File menu, you will see all available skins, then select what you like.