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