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