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