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