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