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