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