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