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