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