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