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