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