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