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