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