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