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