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