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