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