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