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