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