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