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