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