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