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