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