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