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