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