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