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