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)(10,16)(12,26)(13,24)(14,29)(15,22)(17,33)(18,21)(19,35)(20,31)(23,27)(25,37)(28,39)(30,38)(32,34)(36,40) involution — undirected(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)(10,17)(11,23)(13,27)(14,30)(15,28)(16,32)(18,34)(19,36)(20,25)(21,37)(22,38)(24,39)(26,29)(31,40)(33,35) involution — undirected(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.