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