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