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