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