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)(15,16)(17,21)(18,24)(19,23)(20,25)(22,28)(26,27) involution — undirected(1,2)(3,4)(6,9)(10,12)(13,15)(14,20)(16,24)(17,22)(18,25)(19,26)(21,27)(23,28) involution — undirected(5,7,8,11)(6,10,9,12)(14,21)(15,22)(17,19)(23,24)(25,26)(27,28)(2,4)(13,16)(14,22)(15,21)(17,27)(18,20)(19,28)(23,25)(24,26) involution — undirected(6,9)(10,12)(13,17,18,19)(14,23,24,21)(15,22,25,26)(16,27,20,28)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.