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