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)(16,22)(18,19)(25,26)(27,31)(28,32)(29,33)(30,34)(35,39)(36,37)(38,40) involution — undirected(1,2,4,6)(3,5,8,7)(9,10,13,14)(11,15,17,21)(12,16,20,22)(18,23,19,24)(25,27,30,33)(26,31,34,29)(28,36,38,35)(32,37,40,39)(1,2)(3,5)(4,6)(7,8)(25,27)(26,29)(28,35)(30,33)(31,34)(32,37)(36,38)(39,40) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,11)(10,15)(12,19)(13,17)(14,21)(16,24)(18,20)(22,23)(25,27)(26,31)(28,35)(29,34)(30,33)(32,39)(36,38)(37,40) involution — undirected(9,10)(11,15)(12,16)(13,14)(17,21)(18,23)(19,24)(20,22)(25,28,30,38)(26,32,34,40)(27,35,33,36)(29,37,31,39)(9,12,13,20)(10,16,14,22)(11,18,17,19)(15,23,21,24)(25,29,30,31)(26,33,34,27)(28,37,38,39)(32,36,40,35)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.