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