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