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