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