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