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