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