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