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