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