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