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