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