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