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