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