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