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