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