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