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