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