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