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