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