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