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