One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(6,9)(10,12)(13,14)(15,17)(16,18)(19,20)(21,22)(23,25)(24,26)(27,28)(2,3)(22,24)(23,27) involution — undirected(14,15)(18,19)(21,23)(22,25)(24,28)(26,27) involution — undirected(1,3,4,2)(5,6)(7,10)(8,9)(11,12)(13,15,17,14)(16,19,20,18)(21,24,26,22)(23,28,27,25)(5,7,8,11)(6,10,9,12)(13,16,17,20)(14,18,15,19)(21,25,26,28)(22,27,24,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.