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