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