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