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