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