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