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