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