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)(11,18)(12,15)(13,21)(14,17)(16,22)(19,23)(20,24)(25,26,32,31)(27,37,39,33)(28,40,38,34)(29,36,30,35)(2,3)(6,7)(9,10)(11,18)(12,15)(13,16)(14,17)(19,24)(20,23)(21,22)(25,27)(26,33)(28,29)(30,38)(31,37)(32,39)(34,36)(35,40) involution — undirected(4,8)(6,7)(9,11,14,12)(10,15,17,18)(13,19,22,20)(16,23,21,24)(25,28,32,38)(26,34,31,40)(27,29,39,30)(33,36,37,35)(1,3,5,2)(4,7,8,6)(9,12,14,11)(10,15,17,18)(13,20,22,19)(16,23,21,24)(25,29,32,30)(26,35,31,36)(27,28,39,38)(33,40,37,34)(9,13,14,22)(10,16,17,21)(11,19,12,20)(15,23,18,24)(25,30,32,29)(26,36,31,35)(27,38,39,28)(33,34,37,40)(1,4,5,8)(2,6,3,7)(9,10)(11,18)(12,15)(13,16)(14,17)(19,24)(20,23)(21,22)(25,31,32,26)(27,37,39,33)(28,34,38,40)(29,36,30,35)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.