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