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