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