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