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