One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(6,9)(10,12)(13,14,16,18)(15,19,20,17)(21,22,24,25)(23,27,28,26)(1,2,4,3)(13,14)(15,17)(16,18)(19,20)(22,25)(26,27)(2,3)(15,20)(17,19)(21,23,24,28)(22,26,25,27)(5,6)(7,10)(8,9)(11,12)(13,14)(15,17)(16,18)(19,20)(21,22)(23,26)(24,25)(27,28) involution — undirected(1,3,4,2)(5,7,8,11)(6,10,9,12)(13,15,16,20)(14,17,18,19)(21,23)(22,26)(24,28)(25,27)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.