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