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