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