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