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