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