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