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