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