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