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