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