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