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