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