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