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