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