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