The snippet UltimateParent is probably what you want to use, for using the parent dynamically for displaying the menu. In the most simple form, the call looks like this:
[!Wayfinder? &startId=`[[UltimateParent]]` !]
UltimateParent should already be there, if you didn’t exlcude it from the installation. To display your menu like in your example, you probably have to make use of on of the template chunks:
http://www.muddydogpaws.com/development/wayfinder/parameters.html