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