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