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