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