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