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)(13,14,19,23)(15,24,26,16)(17,22,18,21)(20,27,28,25)(5,6)(7,11)(8,10)(9,12)(13,15,19,26)(14,20,23,28)(16,21,24,22)(17,25,18,27)(2,4)(5,7)(6,9)(8,12)(10,11)(13,15)(14,16)(17,27)(18,25)(19,26)(20,22)(21,28)(23,24) involution — undirected(7,12)(9,11)(13,16,19,24)(14,15,23,26)(17,20,18,28)(21,25,22,27)(6,10)(9,11)(13,17,19,18)(14,21,23,22)(15,25,26,27)(16,20,24,28)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.