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