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