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