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