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