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