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