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