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