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