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