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