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