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