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