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