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