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