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