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