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