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