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