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