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