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