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