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