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)(13,14,18,17)(15,19,22,25)(16,20,24,26)(21,27,28,23)(1,2)(3,4)(6,9)(10,12)(13,15)(14,19)(16,23)(17,25)(18,22)(20,21)(24,27)(26,28) involution — undirected(2,4) involution — undirected(2,4)(5,7,8,11)(6,10,9,12)(13,16)(14,20)(15,21)(17,26)(18,24)(19,27)(22,28)(23,25)(6,9)(10,12)(13,14,18,17)(15,19,22,25)(16,20,24,26)(21,27,28,23)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.