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