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)(14,15)(16,20)(18,19)(21,22)(23,24)(29,37)(33,38)(34,39)(36,40) involution — undirected(1,2)(3,7)(4,8)(5,6)(25,26,30,31)(27,28,32,35)(29,33,37,38)(34,36,39,40)(1,3,5,4)(2,7,6,8)(10,15)(11,16)(17,22)(18,23)(26,31)(28,35)(33,38)(36,40)(1,3,5,4)(2,7,6,8)(9,11,14,16)(10,12,15,20)(13,18,21,23)(17,19,22,24)(25,27,30,32)(26,28,31,35)(29,34,37,39)(33,36,38,40)(1,3,5,4)(2,7,6,8)(9,12)(10,16)(11,15)(13,19)(14,20)(17,23)(18,22)(21,24)(25,28)(26,32)(27,31)(29,36)(30,35)(33,39)(34,38)(37,40)(1,4,5,3)(2,8,6,7)(9,13,14,21)(10,17,15,22)(11,18,16,23)(12,19,20,24)(25,29)(26,33)(27,34)(28,36)(30,37)(31,38)(32,39)(35,40)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.