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