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