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