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