Is there a way to use Go Launcher icons in Folder Organizer?
Android applications are distributed as 'apk' files. This is basically just a standard 'zip' file with a different file extension.
If you change the extension to' zip' you can simply extract the contents of any app.
In your particular case the icons will be inside the 'res' folder in one of the folders that have 'drawable'  in their names. 

They're standard 'png' files.