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