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