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