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