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)(12,24)(13,15)(14,28)(16,23)(17,26)(18,27)(20,30)(21,32)(22,33)(25,34)(29,31)(35,36)(37,40)(38,39) involution — undirected(2,6)(7,8)(10,15)(11,20)(14,27)(16,19)(21,37)(22,23)(24,34)(26,29)(30,33)(32,35)(36,38)(39,40) involution — undirected(9,11)(10,16)(12,21)(13,22)(14,20)(15,30)(17,32)(18,33)(19,28)(23,27)(24,35)(25,38)(26,37)(29,36)(31,39)(34,40) involution — undirected(1,3,5,4)(2,7,6,8)(9,12,13,25)(10,17,15,31)(11,21,22,38)(14,29,27,26)(16,32,30,39)(18,34,28,24)(19,35,33,40)(20,36,23,37)(1,4,5,3)(2,7,6,8)(10,15)(16,30)(17,31)(18,28)(19,33)(24,34)(32,39)(35,40)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.