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