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