I've written a bigger project in (SWI-)Prolog. For a better overview about the predicates and the relationships between them, I'm searching for a functionality to illustrate that.
At the XPCE extension (command "manpce") there is an overview about the predicate (Tools > Prolog Navigator). But I'm searching primarily a opportunity to illustrate which predicate calls which predicate and so on...
I suggest you look both at SWI-Prolog own development tools such as gxref as Carlo suggested and at PDT, an Eclipse-based IDE for Prolog programming that supports SWI-Prolog (plus Logtalk, and soon also YAP). PDT includes support for visualizing predicate cross-referencing calls.