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