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