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