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