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