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)(25,26,30,34)(27,29,33,31)(28,35,37,40)(32,36,39,38)(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)(26,31)(28,35)(29,34)(30,33)(32,36)(37,40)(38,39)(2,5)(6,8)(25,28,30,37)(26,32,34,39)(27,35,33,40)(29,38,31,36)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,23)(22,24)(25,26)(27,29)(28,32)(30,34)(31,33)(35,38)(36,40)(37,39)(2,5)(6,8)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,29,30,31)(26,33,34,27)(28,36,37,38)(32,35,39,40)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.