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