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