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