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)(15,22)(16,20)(17,19)(18,24)(21,25)(23,28)(26,27) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,12,11)(13,14,16,20)(15,22,23,28)(17,19,25,21)(18,26,27,24)(5,7,9,8)(6,11,12,10)(13,15,16,23)(14,18,20,27)(17,26,25,24)(19,22,21,28)(2,4)(14,19)(17,25)(18,22)(20,21)(24,26)(27,28) involution — undirected(5,8,9,7)(6,11,12,10)(14,20)(18,27)(19,21)(22,28)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.