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