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