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