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)(11,15,21,31)(12,16,24,34)(13,26,28,17)(19,29,23,33)(20,36,27,30)(22,37,39,32)(25,40,38,35)(9,11)(10,15)(12,22)(13,27)(14,21)(16,32)(17,36)(18,31)(19,25)(20,28)(23,38)(24,39)(26,30)(29,35)(33,40)(34,37) involution — undirected(2,5)(6,8)(9,12)(10,16)(11,19,21,23)(13,25)(14,24)(15,29,31,33)(17,35)(18,34)(20,22,27,39)(26,40)(28,38)(30,32,36,37)(1,3,4,7)(2,6,5,8)(9,11)(10,15)(12,23)(13,20)(14,21)(16,33)(17,30)(18,31)(19,24)(22,38)(25,39)(26,36)(27,28)(29,34)(32,40)(35,37)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.