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