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