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