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