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