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