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