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