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