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