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