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