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