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)(25,26,32,36,31,35,30,34)(27,37,29,28,38,33,40,39)(1,2)(3,7)(4,6)(5,8)(9,11)(10,15)(12,19)(13,22)(14,20)(16,23)(17,18)(21,24)(25,27,31,38)(26,33,35,37)(28,36,39,34)(29,30,40,32)(1,3,4,8)(2,5,6,7)(25,28)(26,29)(27,36)(30,33)(31,39)(32,37)(34,38)(35,40)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,18,24)(25,29)(26,28)(27,30)(31,40)(32,38)(33,36)(34,37)(35,39)(2,6)(5,7)(9,13,14,12)(10,16,17,21)(11,19,20,22)(15,24,18,23)(25,30,31,32)(26,34,35,36)(27,29,38,40)(28,33,39,37)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.