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