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