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