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)(15,19)(18,20)(23,27)(26,28) involution — undirected(6,10)(8,11)(13,14,17,16)(15,18,19,20)(22,25)(26,28)(13,15)(14,18)(16,20)(17,19)(21,22,24,25)(23,26,27,28)(1,2)(3,4)(5,7,9,12)(6,11,10,8)(13,16,17,14)(15,20,19,18)(21,23,24,27)(22,26,25,28)(5,8,9,11)(6,7,10,12)(13,15)(14,18)(16,20)(17,19)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.