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