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