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