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