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