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