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