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)(11,18)(12,20)(13,15)(14,16)(17,21)(19,23)(22,24)(25,26,30,34)(27,33,37,31)(28,38,29,32)(35,39,36,40)(1,2,4,6)(3,5,8,7)(9,11,15,14)(10,16,13,18)(12,19,21,22)(17,23,20,24)(25,27,30,37)(26,31,34,33)(28,35,29,36)(32,39,38,40)(1,2)(3,5)(4,6)(7,8)(25,28,30,29)(26,32,34,38)(27,35,37,36)(31,39,33,40)(1,3)(2,5)(4,8)(6,7)(9,12)(10,17)(11,19)(13,20)(14,22)(15,21)(16,23)(18,24)(25,26)(27,33)(28,32)(29,38)(30,34)(31,37)(35,40)(36,39) involution — undirected(9,13,15,10)(11,16,14,18)(12,20,21,17)(19,23,22,24)(25,27)(26,33)(28,35)(29,36)(30,37)(31,34)(32,40)(38,39)(9,14,15,11)(10,16,13,18)(12,19,21,22)(17,24,20,23)(25,29,30,28)(26,32,34,38)(27,36,37,35)(31,39,33,40)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.