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