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)(25,26,30,34)(27,31,37,32)(28,29,33,39)(35,40,38,36)(1,2)(3,6)(4,5)(7,8)(10,15)(11,18)(17,23)(19,21)(25,27)(26,31)(28,38)(29,36)(30,37)(32,34)(33,35)(39,40) involution — undirected(2,5)(6,8)(10,15)(12,16)(17,23)(20,24)(25,27,30,37)(26,32,34,31)(28,35,33,38)(29,36,39,40)(3,7)(6,8)(9,11)(10,16)(12,15)(13,21)(14,18)(17,20)(19,22)(23,24)(25,28)(26,29)(27,35)(30,33)(31,40)(32,36)(34,39)(37,38) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12,14,16)(10,11,15,18)(13,20,22,24)(17,19,23,21)(25,27)(26,32)(28,35)(29,36)(30,37)(31,34)(33,38)(39,40)(1,3,4,7)(2,6,5,8)(9,13)(10,17)(11,19)(12,20)(14,22)(15,23)(16,24)(18,21)(25,29)(26,33)(27,36)(28,34)(30,39)(31,35)(32,38)(37,40)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.