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