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