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