My お気に入り site for アイコン is Iconomize.com because the アイコン あなた choose automatically installs to your desktop with the shortcut already set. They have the フェイスブック アイコン here, link Just click to install and it goes right on the desktop.
In fact yes あなた can:First あなた go in Google 画像 and type "FACEBOOK ICONS"and save the pic,then あなた go and search"www.iconverticons.com",convert the pic into an アイコン and download it,then go in the desktop: go to"new","shortcut",type:"www.facebook.com",then name it "Facebook",then right click on the shortcut ,go to properties,change アイコン and choose the one あなた converted before,then press APPLY.and then it should come perfect