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