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