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