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