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