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