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