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