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