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