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