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