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