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