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