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