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