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