One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(25,26,29,31)(27,35,36,32)(28,37,38,33)(30,34,39,40)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(26,31)(27,28)(30,39)(32,37)(33,35)(36,38) involution — undirected(2,6)(7,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,27,30,28,29,36,39,38)(26,32,34,33,31,35,40,37)(1,3,5,4)(2,7,6,8)(10,16)(14,17)(15,22)(21,23)(26,31)(27,36)(28,38)(34,40)(1,4,5,3)(2,8,6,7)(11,19)(14,17)(18,24)(21,23)(25,28,30,36,29,38,39,27)(26,33,34,35,31,37,40,32)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.