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