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