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)(13,14,18,22)(15,24,26,16)(17,23,19,21)(20,28,25,27)(1,2)(3,4)(5,7)(6,9)(8,11)(10,12)(13,15)(14,16)(17,20)(18,26)(19,25)(21,28)(22,24)(23,27) involution — undirected(1,3,4,2)(9,12)(13,16,18,24)(14,20,22,25)(15,23,26,21)(17,27,19,28)(13,17,18,19)(14,21,22,23)(15,25,26,20)(16,27,24,28)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.