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