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)(27,33)(28,30)(29,38)(31,37)(32,34)(35,40)(36,39)(1,3,6,2)(4,7,5,8)(9,11,13,18)(10,14,16,22)(12,19,20,17)(15,23,24,21)(26,30)(31,35)(32,38)(33,39)(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(25,27,34,40,28,36,29,37)(26,31,38,39,30,35,32,33)(1,4,6,5)(2,7,3,8)(12,20)(15,24)(17,19)(21,23)(25,26)(27,35)(28,30)(29,32)(31,36)(33,40)(34,38)(37,39)(1,5,6,4)(2,7,3,8)(11,18)(14,22)(17,19)(21,23)(26,30)(31,35)(32,38)(33,39)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.