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