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