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