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