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