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