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