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