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