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