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