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