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