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