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