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