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