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