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