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