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