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