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