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