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