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