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